Russia’s Security Zone in Ukraine: Can Putin Lawfully Hold the Land?

Introduction

On October 16, 2026, Russian President Vladimir Putin announced that Moscow was establishing a security zone inside Ukraine and would not negotiate over its future. Russia’s security zone is intended to extend along the international border, particularly into the Ukrainian regions of Sumy and Kharkiv. Putin presented the operation as necessary to protect Russian territory from cross-border attacks, raising a direct question under international law: can Russia permanently retain Ukrainian land by declaring it essential to its national security?

International law does not permit Russia to acquire sovereignty over Ukrainian territory through military force, occupation, or a unilateral security declaration. It distinguishes between exercising factual control over territory and possessing lawful territorial title. Even where foreign forces establish an occupation, their authority remains subject to international humanitarian law. Occupation does not transfer sovereignty to the occupying power.

The announcement also raises questions about the territory Russia actually controls. Moscow claims substantial progress along Ukraine's northern border, but independent battlefield assessments challenge the scale of its reported advances. The proposed security zone has not been formally annexed as an additional Russian territory, and its intended depth remains uncertain.

Putin's refusal to negotiate over the zone gives the operation significance extending beyond immediate military objectives. A future ceasefire could temporarily preserve existing military positions without recognizing Russian sovereignty. A permanent territorial settlement would raise additional questions concerning the prohibition on acquiring territory through force, the validity of agreements concluded under coercion, and Ukraine's constitutional requirements.

1. Russia’s Security Zone: Territory and Military Claims

Russia's northern security-zone policy seeks to establish a military-controlled strip on the Ukrainian side of the international border. Moscow argues that controlling territory beyond its frontier would provide additional protection against Ukrainian attacks on Russian border settlements and military infrastructure. The proposed area principally concerns Sumy and Kharkiv, two regions of northeastern Ukraine adjoining Russia.

The military reasoning is geographical. By pushing Ukrainian forces farther from the frontier, Russia aims to increase the distance between certain Ukrainian weapons and targets inside Russian territory. The effectiveness of such a zone would depend on its depth, the weapons employed, and Ukraine's capacity to conduct longer-range strikes. Controlling a narrow strip of land would not eliminate threats from missiles or long-range drones.

The territorial implications are more consequential. Russian authorities describe the operation as a defensive measure, but Putin's refusal to include the zone in peace negotiations indicates an intention to preserve Russian control beyond the immediate military campaign. What began as a declared border-security objective has become part of Moscow's negotiating position concerning Ukrainian territory.

1.1 Putin’s October 16 Declaration

Putin made the announcement during a visit to an auxiliary command post of Russia's Joint Grouping of Forces on October 16, 2026. He linked the security-zone operation to Ukraine's military incursion into Russia's Kursk region during 2024–2025 and described the protection of Russian border regions as a continuing objective. He also stated that Moscow would not make the zone a subject of potential peace negotiations with Ukraine.

The declaration connected an ongoing military operation with a proposed restriction on future diplomatic negotiations. Moscow was asserting that territory designated for Russian border security should remain outside discussions over the terms of a settlement. That position may influence Russia's negotiating demands, but it cannot independently determine Ukraine's territorial rights.

An important legal distinction concerns the difference between establishing a security zone and annexing territory. Russia has previously claimed sovereignty over Crimea and four other Ukrainian regions, but the October 16 announcement did not formally incorporate the proposed northern strip into the Russian Federation. A military occupation, an intention to maintain permanent control, and a formal claim of annexation are different acts, although each may have significant consequences under international law.

1.2 How Much Ukrainian Territory Does Russia Control?

Russian officials reported extensive military gains during the October 16 briefing. Kremlin spokesman Dmitry Peskov described a proposed security zone extending approximately 660 kilometers along the border and claimed that Russia controlled about 70 percent of the relevant frontage. Colonel General Yevgeny Nikiforov, commander of Russia's Northern Grouping of Forces, claimed Russian control over approximately 465 kilometers of border frontage in the Kursk and Belgorod directions.

Nikiforov also claimed that Russian forces had captured more than 3,000 square kilometers since the establishment of the security-zone policy in March 2024. This was presented as a cumulative territorial-gains figure, not as an independently established measurement of the area under Russian occupation on October 16, 2026.

The Institute for the Study of War (ISW) challenged Moscow's account. Its October 16 assessment identified evidence supporting Russian control of approximately 205.77 square kilometers within a defined northern security-strip study area, extending from the E101 Kyiv–Hlukhiv highway to the contiguous frontline in the Velykyi Burluk direction. ISW also reported that it had not confirmed new Russian advances in northern Sumy or northern Kharkiv during October 15–16.

The measurements describe different geographical and temporal categories. Russia's 465-kilometer figure concerns the length of border frontage it claims to control, while ISW's 205.77-square-kilometer figure concerns territorial area within a specified sector. Neither can be directly converted into the other. The Russian claim of more than 3,000 square kilometers also covers a substantially longer period than ISW's assessment of current control.

The available evidence establishes a significant discrepancy between Russian military claims and independently documented territorial control. It does not establish that Moscow exercises authority throughout the declared security zone. This uncertainty is legally relevant because occupation depends on actual control over identifiable territory, rather than the geographical boundaries asserted by an army.

1.3 Russia’s Buffer-Zone Policy Before and After Kursk

The northern security-zone policy predates Putin's October 2026 declaration. In March 2024, he publicly suggested creating a buffer zone inside Ukraine to protect Russian border regions. Following a new Russian offensive into northern Kharkiv on May 10, 2024, Putin stated on May 17 that Russian forces were establishing such a zone in response to attacks affecting Belgorod.

Ukraine's incursion into Russia's Kursk region began in August 2024, several months after Moscow had announced and begun implementing the buffer-zone policy. Ukrainian forces crossed the international border and conducted operations inside Russian territory. Moscow subsequently invoked those operations as justification for further measures to secure its frontier.

The policy expanded into the Sumy region during 2025. At the St. Petersburg International Economic Forum on June 20, 2025, Putin described a buffer zone extending approximately 8–12 kilometers into Sumy and stated that Russian forces might advance toward the regional capital, although he said capturing the city was not their immediate objective.

By October 2026, Moscow was presenting the security strip as an enduring military requirement. The latest declaration introduced a more explicit diplomatic consequence: Russian-controlled territory associated with the operation would not, according to Putin, be available for negotiation. That position does not create sovereign rights, but it raises the possibility of a prolonged Russian military presence in northern Ukraine.

2. Are Buffer Zones Legal Under International Law?

International law does not categorically prohibit military buffer zones. States may establish demilitarized areas, ceasefire separation zones, or mutually agreed security arrangements to reduce the risk of renewed hostilities. Their legality depends on the authority establishing them, the terms governing their operation, and the obligations accepted by the parties.

Article 60 of Additional Protocol I to the Geneva Conventions regulates a specific category of demilitarized zone established by agreement between parties to an armed conflict. Such agreements normally provide for the evacuation of combatants and mobile military equipment, the cessation of hostile activities, and restrictions on military use. The parties may also define geographical boundaries and arrangements for supervision.

The provision serves a humanitarian purpose by protecting designated areas from military operations contrary to the agreement. It does not establish a general legal framework for every security zone or buffer strip. Nor does it authorize one belligerent to enter another state's territory, maintain troops there, and acquire territorial rights merely by describing the area as demilitarized.

Russia's proposed security zone differs from an agreed demilitarized area under Article 60. Moscow intends to maintain military forces on Ukrainian territory to prevent attacks against Russia. No Ukrainian agreement authorizing the proposed arrangement has been established, and no applicable UN Security Council authorization has been identified.

A buffer zone could form part of a lawful agreement between Russia and Ukraine, including arrangements for troop separation or restrictions on military deployments. A unilateral military zone would require its own justification under the rules governing the use of force. The expression security zone supplies no independent legal exception to those rules and cannot extinguish Ukraine's territorial sovereignty.

3. The UN Charter and Russia’s Claim of Self-Defense

The legality of Russia's military presence must first be assessed under the rules governing the resort to force, commonly described as jus ad bellum. These rules determine when a state may lawfully employ armed force against another state. They operate separately from international humanitarian law, which regulates military conduct and protects persons affected by armed conflict.

Moscow's stated objective is to prevent further attacks against its border regions. Attacks on Russian territory can raise genuine security concerns, but their legal significance must be assessed within the wider armed conflict. Russia launched its full-scale invasion of Ukraine on February 24, 2022, and Ukraine has since conducted military operations in response, including strikes and incursions across the internationally recognized border.

The central question is whether Russia can invoke threats arising during that conflict to justify establishing additional military control inside Ukraine. International law does not recognize a general entitlement to occupy neighboring territory merely because a government regards that arrangement as strategically advantageous.

3.1 Article 2(4) and Ukraine’s Territorial Integrity

Article 2(4) of the UN Charter prohibits the threat or use of force against the territorial integrity or political independence of another state, or in any other manner inconsistent with the purposes of the United Nations. The provision protects Ukraine's sovereignty regardless of the extent of Russian military control. Describing an operation as defensive, temporary, or geographically limited does not exempt it from the prohibition.

The International Court of Justice confirmed in its 1986 judgment in Military and Paramilitary Activities in and against Nicaragua that the prohibition on the use of force also forms part of customary international law. The Court distinguished unlawful military intervention from the exceptional circumstances in which force may be justified under the right of self-defense.

The internationally recognized boundary between Russia and Ukraine remains legally distinct from the current military frontline. Russia's capture of Ukrainian territory does not, by itself, alter that boundary. This principle has been repeatedly affirmed by the UN General Assembly during the conflict.

On March 2, 2022, the General Assembly adopted Resolution ES-11/1, demanding Russia's withdrawal from Ukraine. In October 2022, Resolution ES-11/4 rejected Moscow's attempted annexations of Donetsk, Luhansk, Kherson, and Zaporizhzhia and reaffirmed Ukraine's sovereignty within its internationally recognized borders. These resolutions express the General Assembly's position; they are not binding judicial judgments.

The ICJ also ordered Russia to suspend the military operations it had commenced in Ukraine in its provisional measures order of March 16, 2022, in Allegations of Genocide under the Genocide Convention (Ukraine v. Russia). The Court subsequently delivered a preliminary-objections judgment on February 2, 2024, concerning the scope of its jurisdiction under the Genocide Convention.

The proceedings continued. On December 5, 2025, the ICJ found Russia's counterclaims admissible as such and authorized further written pleadings by both parties. That procedural decision did not determine whether Ukraine had committed genocide or resolve the merits of the parties' claims. Neither the 2024 judgment nor the 2025 order constituted a final determination of the legality of Russia's military operations under Article 2(4) of the UN Charter.

3.2 Can the Kursk Incursion Justify Article 51?

Article 51 of the UN Charter preserves the inherent right of individual or collective self-defense if an armed attack occurs. Russia may invoke Ukrainian military operations inside Kursk and attacks affecting its border regions as grounds for defensive action. The existence of such attacks cannot be disregarded solely because they occurred during an ongoing war.

Their legal characterization nevertheless depends on the circumstances. Ukraine's operations arose in the context of Russia's earlier invasion and Ukraine's continuing right of self-defense. The fact that Ukrainian forces crossed into Russian territory does not automatically establish that Moscow acquired a new entitlement to occupy additional Ukrainian land.

The ICJ addressed the requirements of necessity and proportionality in Nicaragua v. United States. Necessity concerns whether force is required to respond to an armed attack. Proportionality concerns the relationship between the defensive action and the legitimate defensive objective. These are restrictions on the resort to force and must be distinguished from the separate humanitarian-law test governing incidental civilian harm during individual attacks.

Russia's security argument also invites comparison with Armed Activities on the Territory of the Congo (DRC v. Uganda). Uganda relied on security threats arising from armed groups operating from Congolese territory. The Court did not accept that the circumstances established a lawful justification for Uganda's military intervention and found violations of the DRC's sovereignty and territorial integrity.

That judgment does not establish that every cross-border defensive operation is unlawful. It demonstrates, however, that general security concerns do not displace the conditions governing self-defense. The scale, purpose, necessity, and duration of a military operation remain legally relevant.

Putin's proposed arrangement raises a further problem because it is associated with indefinite territorial retention. Even when a particular use of force satisfies Article 51, self-defense does not confer sovereignty over territory occupied during the operation. Nor does a claimed defensive necessity authorize continued military control after the legal justification for that control has ceased. Russia's intention to keep the security zone outside peace negotiations cannot resolve either question.

4. Does the Security Zone Constitute Occupied Territory?

International humanitarian law determines occupation according to the actual exercise of authority over foreign territory. A state cannot establish or avoid the legal classification merely by describing its operation as a security mission, defensive intervention, or temporary deployment. If Russian forces exercise the required degree of control over Ukrainian territory without valid Ukrainian consent, the law of belligerent occupation applies.

Occupation must be distinguished from the legality of the intervention itself. An occupying power may be acting unlawfully under the UN Charter while simultaneously being bound by the rules of occupation. Those rules impose obligations because foreign military forces exercise authority over territory and its inhabitants, irrespective of whether their initial entry was lawful.

The proposed northern zone cannot automatically receive a single legal classification. Russian-held settlements, contested villages, and Ukrainian-controlled localities may occupy different positions under international humanitarian law. The relevant inquiry concerns the geographical areas in which Russian forces have established authority capable of replacing that of Ukraine.

4.1 Effective Control and the ICJ’s Uganda Judgment

Article 42 of the 1907 Hague Regulations establishes that territory is occupied when it is actually placed under the authority of a hostile army. Occupation extends only to areas where that authority has been established and can be exercised. Temporary military incursions or isolated troop positions do not necessarily establish occupation, although permanent deployment in every locality is not required.

The ICJ applied this principle in its December 19, 2005, judgment in Armed Activities on the Territory of the Congo. The Court examined whether Ugandan forces had substituted their authority for that of the Congolese government. It concluded that Uganda exercised authority as an occupying power in the Ituri district, where sufficient evidence of effective control existed.

The Court declined to characterize every location where Ugandan troops were stationed as occupied territory. It found insufficient evidence that Uganda exercised the necessary authority in certain other areas. Military presence and occupation were consequently treated as related but legally distinct conditions.

Applied to Russia's security zone, this reasoning requires an assessment of actual military and administrative authority. Russian control over a settlement may support a finding of occupation if Ukrainian governmental authority has been displaced. The Russian military's declaration of a wider operational perimeter does not establish occupation throughout that area.

Once occupation exists, the occupying power assumes legal responsibilities toward the civilian population. Those duties continue while the relevant conditions of occupation persist, even if Ukrainian forces contest Russian control or the occupying power describes its presence as temporary.

4.2 Civilian Protection in Sumy and Kharkiv

Article 43 of the Hague Regulations obliges an occupying power to take measures within its power to restore and ensure public order and civil life while respecting existing laws unless absolutely prevented. The obligation concerns the administration of territory under foreign military authority, including the protection of residents and the functioning of essential civilian institutions.

The Fourth Geneva Convention provides additional safeguards. Article 55 requires an occupying power, to the fullest extent of its available means, to ensure food and medical supplies for the population. Other provisions regulate humanitarian relief, detention, public health, and the treatment of protected persons. These obligations are particularly significant where military operations disrupt access to medical care, electricity, transport, and essential supplies.

The humanitarian consequences of fighting in northern Ukraine are substantial. According to the UN Human Rights Monitoring Mission in Ukraine, at least 11 civilians were killed and 131 injured in the city of Sumy during September 2026. Across Ukraine, the Mission recorded 328 civilians killed and 2,105 injured during that month, with long-range missiles and drones accounting for the largest share of casualties.

These figures concern the wider armed conflict and cannot automatically be attributed to Russia's security-zone operation. Establishing responsibility for particular incidents requires evidence of the circumstances, the forces involved, and the applicable legal rules. Civilian casualties alone do not establish that every attack violated international humanitarian law.

Displacement raises separate obligations where occupation has been established. Article 49 of the Fourth Geneva Convention prohibits forcible transfers and deportations of protected persons from occupied territory, subject to narrowly defined exceptions for evacuations required by civilian security or imperative military reasons. Such evacuations are temporary, and the Convention requires evacuees to be returned to their homes as soon as hostilities in the area concerned have ceased.

An occupying power also may not transfer parts of its own civilian population into occupied territory. Nor may it use military administration to permanently displace the existing population. These restrictions limit the extent to which territorial security objectives may affect civilian residence and demographic conditions.

In areas where occupation has not been established, the rules governing the conduct of hostilities remain applicable. Both parties must distinguish civilians from combatants, direct attacks only against lawful military objectives, and comply with the applicable proportionality and precautionary requirements. Civilian protection does not depend on which army ultimately controls the territory.

5. Occupation, Sovereignty, and Permanent Territorial Control

Military control over foreign territory does not establish lawful sovereignty. An army may occupy territory for an extended period without acquiring the right to incorporate it into its own state. The law of belligerent occupation recognizes limited authority exercised during armed conflict, but it does not permit that authority to become a source of territorial title.

Article 47 of the Fourth Geneva Convention protects civilians in occupied territory against the loss of Convention safeguards resulting from changes in local institutions, agreements with authorities in the occupied territory, or annexation by the occupying power. The provision reflects the principle that foreign military administration cannot extinguish the legal protections attached to occupation.

The ICJ examined the relationship between occupation and sovereignty in its July 19, 2024, advisory opinion, Legal Consequences arising from the Policies and Practices of Israel in the Occupied Palestinian Territory, including East Jerusalem. The Court explained that occupation is inherently temporary and does not transfer sovereign title to the occupying power. Prolonged military authority cannot, by itself, establish lawful ownership of foreign territory.

In paragraphs 253–254 of the advisory opinion, the Court stated that occupation cannot serve as a source of territorial title or justify acquisition by the occupying power. Addressing Israel's policies and practices in the Occupied Palestinian Territory, it concluded that security concerns could not override the prohibition on acquiring territory through force.

The advisory opinion concerned a different territorial situation, and its findings regarding the illegality of Israel's continued presence were based on the particular circumstances before the Court. Its broader reasoning remains relevant to Russia because the prohibition on territorial acquisition through force is a rule of general international law. The advisory opinion was not a judgment on Russia's proposed security zone, and its situation-specific conclusions cannot simply be transferred to Ukraine.

Russia's previous annexation claims illustrate the difference between asserted sovereignty and internationally recognized territorial title. Moscow declared the annexation of Crimea in 2014 and purported to annex Donetsk, Luhansk, Kherson, and Zaporizhzhia in 2022. Ukraine and the overwhelming majority of UN member states have rejected those territorial claims. The October 2026 announcement differs because Russia has not formally presented the proposed northern security strip as an additional annexed territory.

The absence of formal annexation does not automatically establish that indefinite military retention would be lawful. Continued foreign military authority must still comply with the rules governing the use of force, occupation, and territorial sovereignty. Measures designed to integrate occupied territory permanently into the occupying state could raise additional questions concerning attempted annexation, even without an immediate formal declaration.

International law also imposes responsibilities on other states when serious violations create unlawful territorial situations. Articles 40 and 41 of the International Law Commission's 2001 Articles on State Responsibility address serious breaches of obligations arising under peremptory norms of general international law. Their special consequences apply where the breach involves a gross or systematic failure to fulfill such an obligation.

Article 41 provides for non-recognition of situations created by qualifying serious breaches and prohibits aid or assistance in maintaining them. The Articles are not themselves a treaty, and individual provisions require attention to their customary-law status. The prohibition on recognizing territorial acquisition resulting from unlawful force has substantial support in international practice and international judicial reasoning.

Non-recognition does not prohibit every form of practical contact with authorities exercising factual control. States and humanitarian organizations may need to communicate with occupying forces concerning civilian protection, relief deliveries, or evacuations. Such engagement does not necessarily recognize sovereignty. The legal distinction concerns assistance that maintains an unlawful situation or conduct that treats an unlawful territorial acquisition as valid.

6. Can Putin Exclude the Zone From a Peace Settlement?

Putin's declaration that the security zone will not be negotiable expresses Russia's political position. It does not constitute a binding territorial determination under international law. Moscow may demand continued military control, refuse territorial concessions, or insist on particular security conditions. Those demands cannot, by themselves, extinguish Ukraine's sovereignty or establish a new internationally recognized border.

Military control may nevertheless influence the practical terms of negotiations. A state occupying disputed territory may seek to use its battlefield position to obtain concessions, and an agreement ending hostilities may need to address the location of forces already deployed. The ability to impose military pressure is distinct from the legal entitlement to obtain the resulting territorial arrangement.

Ukraine has rejected Russian claims to sovereignty over occupied Ukrainian territory. Negotiations over a ceasefire or security arrangements could proceed without Kyiv recognizing Russian territorial ownership. International law permits parties to regulate military deployments while leaving the underlying question of sovereignty unresolved.

6.1 Ceasefire Lines and Temporary Security Arrangements

A ceasefire ordinarily regulates the suspension of hostilities rather than transferring sovereignty. Parties may agree to stop fighting along existing positions, withdraw certain units, establish monitoring mechanisms, or restrict military deployments within specified areas. Such arrangements may reduce immediate risks without determining the final international boundary.

This distinction is particularly relevant to the proposed Russian security zone. A future agreement could regulate the presence or withdrawal of military forces in northern Ukraine without recognizing Russian sovereignty. Ukraine might accept a temporary separation arrangement while maintaining its territorial claims. The legal consequences would depend on the terms of the agreement, the circumstances of its conclusion, and the authority exercised over the affected territory.

A ceasefire does not automatically terminate an occupation. If Russian forces continue exercising effective authority over Ukrainian territory after hostilities are suspended, occupation law may remain applicable. Russia would retain the corresponding obligations toward protected persons while the relevant conditions of occupation persist.

Temporary security arrangements also require clarity concerning their geographical scope, duration, supervision, and termination. An agreement providing for restricted military deployments is legally different from one purporting to give a foreign state indefinite sovereign authority. Neither the existence of a ceasefire nor the preservation of a military frontline changes territorial title without a separate lawful basis.

6.2 Territorial Cession, Coercion, and Ukrainian Consent

A permanent transfer of Ukrainian territory would face more demanding legal requirements. Article 52 of the Vienna Convention on the Law of Treaties provides that a treaty is void if its conclusion was procured through the threat or use of force contrary to the principles of international law embodied in the UN Charter. The provision protects the validity of state consent against prohibited coercion.

Not every agreement concluded during an armed conflict is automatically invalid. States may lawfully negotiate ceasefires, peace agreements, and other instruments while hostilities continue. The decisive questions concern whether the agreement was procured through prohibited force, whether the parties validly consented, and whether its terms comply with other applicable international obligations.

Ukraine's Constitution imposes additional domestic requirements. Article 73 reserves decisions concerning changes to Ukraine's territory exclusively to an all-Ukrainian referendum. Article 157 prohibits constitutional amendments aimed at eliminating Ukraine's independence or violating its territorial integrity. It also prohibits amendments to the Constitution during martial law or a state of emergency.

Ukraine's Law on the Legal Regime of Martial Law imposes further restrictions. Article 19 prohibits the holding of all-Ukrainian and local referendums during martial law. Article 20 of the Law on All-Ukrainian Referendums separately prohibits the calling and holding of an all-Ukrainian referendum while martial law or a state of emergency is in effect.

These restrictions are directly relevant to any proposal involving Ukrainian territorial concessions. Martial law remains in force in Ukraine as of October 17, 2026, following its extension from August 2 through October 31, 2026. A territorial referendum cannot lawfully be conducted while the applicable wartime prohibition remains in effect.

The constitutional restrictions would continue to require consideration even after martial law ends. The requirement for a referendum does not mean that any territorial proposal submitted to voters would automatically become lawful. Article 157 and other applicable constitutional provisions constrain the changes that Ukrainian state institutions may pursue.

The relationship between domestic constitutional restrictions and international treaty law requires a separate assessment. Article 46 of the Vienna Convention provides that a state may invoke a violation of its internal law concerning competence to conclude treaties as invalidating consent only when the violation was manifest and concerned a rule of fundamental importance. A manifest violation is one objectively evident to another state acting in accordance with normal practice and good faith.

Articles 46 and 52 address different grounds of invalidity. Article 46 concerns the state's constitutional authority to express treaty consent, while Article 52 concerns coercion through prohibited force. An agreement cannot be assessed adequately by considering only one provision or by assuming that a domestic constitutional defect necessarily produces international invalidity.

These restrictions are relevant to any demand that Ukraine permanently transfer territory to Russia as part of a settlement. Putin's refusal to negotiate the security zone cannot substitute for Ukraine's legally valid consent. Nor would military control alone establish the validity of a treaty purporting to transfer sovereign title.

Conclusion

Putin cannot lawfully acquire Ukrainian territory merely by establishing a security zone inside Ukraine or declaring that Russia must retain it for border protection. The UN Charter restricts the use of force against another state's territorial integrity, and military occupation does not transfer sovereignty. Russia's assertion that the zone is essential to its national security creates no independent legal entitlement to Ukrainian land.

Russian forces may continue exercising factual control over particular areas while the conflict persists, although the geographical extent of that control remains disputed. Where the conditions of occupation are satisfied, Russia must comply with the obligations imposed by international humanitarian law. Those obligations remain applicable even when the military presence itself is unlawful.

A future ceasefire could preserve military positions temporarily or establish agreed security arrangements without recognizing Russian sovereignty. A purported permanent transfer would raise different questions involving the prohibition on territorial acquisition through force, the validity of treaty consent, and Ukraine's constitutional restrictions. Putin's refusal to negotiate cannot independently resolve those questions.

The legally decisive issue is not how long Russian troops can remain in northern Ukraine, but whether Russia possesses a lawful basis for its presence and any territorial rights it claims. Military control may determine who administers a territory in practice. It cannot, through occupation or a unilateral declaration, turn Ukrainian land into sovereign Russian territory.

References

Charter of the United Nations (1945) Signed at San Francisco, 26 June 1945; entered into force 24 October 1945, 1 UNTS XVI. Available at: https://www.un.org/en/about-us/un-charter (Accessed: 17 October 2026).

Constitution of Ukraine (1996) Adopted 28 June 1996, Law No. 254к/96-ВР, as amended. Verkhovna Rada of Ukraine. Available at: https://zakon.rada.gov.ua/laws/show/en/254%D0%BA/96-%D0%B2%D1%80 (Accessed: 17 October 2026).

Convention (IV) relative to the Protection of Civilian Persons in Time of War (1949) Geneva, 12 August 1949; entered into force 21 October 1950, 75 UNTS 287. Available at: https://ihl-databases.icrc.org/en/ihl-treaties/gciv-1949 (Accessed: 17 October 2026).

Convention (IV) respecting the Laws and Customs of War on Land and its Annex: Regulations concerning the Laws and Customs of War on Land (1907) The Hague, 18 October 1907; entered into force 26 January 1910. Available at: https://ihl-databases.icrc.org/en/ihl-treaties/hague-conv-iv-1907/regulations-art-42 (Accessed: 17 October 2026).

Human Rights Monitoring Mission in Ukraine (2026) Protection of Civilians in Armed Conflict — September 2026. 15 October. Office of the United Nations High Commissioner for Human Rights. Available at: https://ukraine.ohchr.org/en/Protection-of-Civilians-in-Armed-Conflict-September-2026 (Accessed: 17 October 2026).

Interfax (2025) ‘Buffer zone in Sumy region is around 10–12 km deep — Putin (Part 3)’ [online]. 20 June. Available at: https://www.interfax-russia.ru/military/news_eng/424239 (Accessed: 17 October 2026).

Interfax (2026) ‘Военные РФ контролируют 70% госграницы на курском и белгородском направлениях’ [Russian military controls 70% of the state border in the Kursk and Belgorod directions] [online]. 16 October. Available at: https://www.interfax.ru/russia/1123071 (Accessed: 17 October 2026).

International Court of Justice (1986) Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment of 27 June 1986, ICJ Reports 1986, p. 14. Available at: https://www.icj-cij.org/node/103143 (Accessed: 17 October 2026).

International Court of Justice (2005) Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v. Uganda), Judgment of 19 December 2005, ICJ Reports 2005, p. 168. Available at: https://www.icj-cij.org/index.php/node/103161 (Accessed: 17 October 2026).

International Court of Justice (2022) Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v. Russian Federation), Provisional Measures, Order of 16 March 2022, ICJ Reports 2022, p. 211. Available at: https://www.icj-cij.org/node/106135 (Accessed: 17 October 2026).

International Court of Justice (2024a) Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v. Russian Federation: 32 States intervening), Preliminary Objections, Judgment of 2 February 2024. Available at: https://www.icj-cij.org/index.php/node/203503 (Accessed: 17 October 2026).

International Court of Justice (2024b) Legal Consequences arising from the Policies and Practices of Israel in the Occupied Palestinian Territory, including East Jerusalem, Advisory Opinion of 19 July 2024. Available at: https://www.icj-cij.org/index.php/node/204160 (Accessed: 17 October 2026).

International Court of Justice (2025) Allegations of Genocide under the Convention on the Prevention and Punishment of the Crime of Genocide (Ukraine v. Russian Federation), Counter-Claims; Fixing of Time-Limits: Reply and Rejoinder, Order of 5 December 2025. Available at: https://www.icj-cij.org/case/182 (Accessed: 17 October 2026).

International Law Commission (2001) Draft Articles on Responsibility of States for Internationally Wrongful Acts, with Commentaries. Yearbook of the International Law Commission, 2001, Vol. II, Part Two, UN Doc. A/56/10, Chapter IV.E.1. Available at: https://legal.un.org/ilc/texts/instruments/english/commentaries/9_6_2001.pdf (Accessed: 17 October 2026).

Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) (1977) Geneva, 8 June 1977; entered into force 7 December 1978, 1125 UNTS 3. Available at: https://treaties.un.org/Pages/showDetails.aspx?objid=08000002800f3586 (Accessed: 17 October 2026).

Reuters (2024a) ‘Kremlin says the only way to protect Russia is to create a buffer zone with Ukraine’ [online]. 18 March. Available at: https://www.reuters.com/world/europe/kremlin-says-only-way-protect-russia-is-create-buffer-zone-with-ukraine-2024-03-18/ (Accessed: 17 October 2026).

Reuters (2024b) ‘Putin says Russia is carving out a buffer zone in Ukraine’s Kharkiv region’ [online]. 17 May. Available at: https://www.reuters.com/world/europe/putin-says-russia-is-carving-out-buffer-zone-ukraines-kharkiv-region-2024-05-17/ (Accessed: 17 October 2026).

Reuters (2026) ‘Putin says Russia is building non-negotiable “security zone” in Ukraine along border’ [online]. 16 October. Available at: https://www.reuters.com/world/putin-says-russia-is-building-non-negotiable-security-zone-ukraine-along-border-2026-10-16/ (Accessed: 17 October 2026).

Shymkiv, K., Sundstrom, N., Harward, C. and Barros, G. (2026) ‘Russian Offensive Campaign Assessment, October 16, 2026’ [online]. Institute for the Study of War and Critical Threats Project, 16 October. Available at: https://www.criticalthreats.org/analysis/russian-offensive-campaign-assessment-october-16-2026 (Accessed: 17 October 2026).

United Nations General Assembly (2022a) Aggression against Ukraine, Resolution ES-11/1, UN Doc. A/RES/ES-11/1, adopted 2 March 2022. Available at: https://docs.un.org/A/RES/ES-11/1 (Accessed: 17 October 2026).

United Nations General Assembly (2022b) Territorial Integrity of Ukraine: Defending the Principles of the Charter of the United Nations, Resolution ES-11/4, UN Doc. A/RES/ES-11/4, adopted 12 October 2022. Available at: https://docs.un.org/A/RES/ES-11/4 (Accessed: 17 October 2026).

Verkhovna Rada of Ukraine (2015) Law of Ukraine on the Legal Regime of Martial Law, Law No. 389-VIII, adopted 12 May 2015, as amended. Available at: https://zakon.rada.gov.ua/laws/show/389-19 (Accessed: 17 October 2026).

Verkhovna Rada of Ukraine (2021) Law of Ukraine on All-Ukrainian Referendums, Law No. 1135-IX, adopted 26 January 2021, as amended. Available at: https://zakon.rada.gov.ua/laws/show/1135-20 (Accessed: 17 October 2026).

Verkhovna Rada of Ukraine (2026) Law of Ukraine on Approval of the Presidential Decree on Extension of Martial Law in Ukraine, Law No. 4928-IX, adopted 14 July 2026. Available at: https://zakon.rada.gov.ua/laws/show/4928-20 (Accessed: 17 October 2026).

Vienna Convention on the Law of Treaties (1969) Vienna, 23 May 1969; entered into force 27 January 1980, 1155 UNTS 331. Available at: https://treaties.un.org/Pages/ViewDetailsIII.aspx?chapter=23&mtdsg_no=XXIII-1&src=TREATY (Accessed: 17 October 2026).