Introduction
The prospect of a peace agreement between Russia and Ukraine facilitated by the United States raises significant questions regarding its legal validity under international law, particularly given Russia’s use of force since 2014.
FAF’s Defense.Forum examines whether such an agreement would be legally binding, what role the UN Security Council might play, and the implications for sustainable peace.
The Legal Status of Treaties Procured Through Force
International law is unequivocal on the validity of treaties procured through coercion.
Article 52 of the Vienna Convention on the Law of Treaties (1969) explicitly states: “A treaty is void if its conclusion has been procured by the threat or use of force in violation of the principles of international law embodied in the Charter of the United Nations.”
This principle represents a significant evolution from traditional international law, which historically accepted the validity of treaties procured through military force.
The prohibition against treaties procured through coercion is considered a peremptory norm (jus cogens) of international law, reflecting the fundamental shift in the global legal order following World War II.
The international community recognized that for peace to be sustainable, it must be founded on consent that is freely given, not extracted through military pressure or occupation.
Annexation, defined as “one state forcibly acquiring another state’s territory, usually through a treaty or use of force,” is prohibited under contemporary international law.
Annexation treaties are particularly problematic because they “often involve an element of coercion” where “the state ceding territory either is compelled to sign a peace treaty after a military defeat or is represented by a puppet government willing to accept the annexation.”
Application to the Russia-Ukraine Context
Russia’s actions in Ukraine since 2014, including the annexation of Crimea and military operations in eastern Ukraine, constituted the use of force under international law.
The full-scale invasion launched in February 2022 further exemplifies this use of force.
While Russia has attempted to justify its actions as self-defense under Article 51 of the UN Charter, international legal experts have widely rejected this claim.
Russia’s Permanent Representative to the United Nations notified the UN Secretary-General that its military action was “taken by Article 51 of the UN Charter in the exercise of the right of self-defense.”
Still, the international community has not accepted this justification.
Under a strict application of Article 52 of the Vienna Convention, any peace agreement between Ukraine and Russia that results directly from this use of force would be legally void.
This would mean that Ukraine could legally repudiate such an agreement in the future, creating significant instability and uncertainty.
The Potential Role of the UN Security Council
The UN Security Council possesses unique powers under Chapter VII of the UN Charter that could potentially affect the legal status of a Russia-Ukraine peace agreement.
The Security Council has what some scholars describe as “constitutive powers” that allow it to take actions that might deviate from other international legal norms when acting to maintain or restore international peace and security.
The Security Council’s powers are purposive and effectiveness-oriented, meaning they are interpreted broadly to enable the Council to fulfill its primary responsibility of maintaining international peace and security.
One scholar notes, “The Council may create new law for the concrete case.”
This raises an important question: Could the Security Council effectively validate a peace agreement that would otherwise be void under Article 52?
Some legal scholars argue that while Article 52 of the Vienna Convention declares treaties procured through coercion as void, the Security Council, acting under Chapter VII, might have the authority to endorse such agreements in certain circumstances.
The argument is that “what is decisive… is for the Security Council to affirm that the unilateral act is to be by the ends of the United Nations.
Whether this happens in advance or arrears does not appear to make such a fundamental difference.”
This suggests that the Security Council's endorsement could potentially overcome the legal defect of coercion.
Article 103 of the UN Charter, establishing “the primacy of states’ obligations under the Charter over their other international obligations,” further supports the Security Council's potential role.
This provision could mean that Security Council resolutions endorsing a peace agreement would precede obligations under the Vienna Convention.
Challenges and Implications
Several challenges and implications arise from this analysis
Security Council Politics
Russia is a permanent member of the Security Council with veto power.
While this ensures Russia could not be forced to accept a resolution it opposes, other permanent members could block an attempt to validate a peace agreement they view as unjust or contrary to international law.
Legitimacy vs. Legality
Even if the Security Council endorsed a peace agreement, questions about its legitimacy might persist if the agreement is perceived as rewarding aggression or undermining territorial integrity.
Precedent-Setting
Security Council validation of an agreement resulting from force could set a concerning precedent, potentially undermining the prohibition against using force in international relations.
Long-term Stability
A peace agreement viewed as legally questionable may lack the stability needed for long-term peace, as future Ukrainian governments might challenge its validity.
Conclusion
The legal status of any Russia-Ukraine peace agreement will depend significantly on whether and how the UN Security Council is involved.
While treaties procured through force are generally void under international law, Security Council endorsement could provide legal validity to such an agreement.
For the Trump administration or any mediator seeking a legally sustainable peace agreement, early involvement of the UN Security Council in the peace process would be advisable.
Rather than attempting to secure a bilateral agreement first and seeking UN endorsement later, incorporating the Security Council from the outset could help ensure that any resulting agreement has a stronger claim to legal validity.
Such an approach would need to balance pragmatic considerations about ending the conflict with principled concerns about not legitimizing territorial acquisition through force.
Finding this balance will be essential for creating a temporary cessation of hostilities and a legally sound and sustainable peace that respects the fundamental principles of international law.
