Yuri Kobzar21:33, 08.05.25

If Ukraine does not return all of its territories, the terms of the agreement will be considered imposed by force, which violates international law.

Any peace treaty between Ukraine and Russia that does not fully restore Ukrainian sovereignty over its entire constitutional territory will be inherently illegal and easily challenged, writes Duncan Hollis, a law professor at Temple University and editor of the Oxford Handbook of International Treaties, in a Foreign Policy article.

He refers to the Vienna Convention on the Law of Treaties of 1980. It has been signed and is therefore binding on 116 states around the world, including Russia and Ukraine. The United States has not signed the convention, but in practice recognizes most of its provisions.

“A treaty has no legal force if its conclusion was achieved through the threat or use of force in violation of the principles of international law enshrined in the Charter of the United Nations,” states Article 52 of this convention.

Hollis emphasizes that international law, which existed before World War II, allowed states to use military force to force others to conclude international treaties. However, the UN Charter, developed under US leadership in response to World War II, fundamentally changed this situation.

This charter prohibits the use of force except in self-defense or with the sanction of the UN Security Council. The idea was precisely to prevent anything like the infamous Munich Agreement of 1938, when Britain, France, and Italy ceded part of Czechoslovakia to Nazi Germany.

In the past, the International Court of Justice has already recognized Article 52 as a norm of customary international law that is binding on all states.

Since Russian aggression against Ukraine cannot in any way be recognized by international bodies as self-defense, this war is illegal from the point of view of international law.

Under such circumstances, even if Ukraine agrees to territorial concessions in one form or another, they will be considered a result achieved through the illegal use of force. And this makes the peace treaty legally invalid.

The lawyer believes that for these reasons, neither side will be able to apply sanctions or other countermeasures against the other in case of violation of the terms of the agreement. Instead of lasting peace, this will lead to dangerous instability, since both Ukraine and Russia can simply declare the agreement invalid. Third countries will also have the right to refuse to recognize the agreement.

The only real option to give legal force to the peace agreement between Ukraine and the Russian Federation is to ratify it through the UN Security Council. Such a precedent already existed in 1999, when it was necessary to end the war in Kosovo, and in 2000 after the war between Ethiopia and Eritrea.

However, this scenario means that all countries on the UN Security Council, including the UK, France and China, must give their consent.

(C)UNIAN 2025