Considering the ongoing conflict and the historical context, the “biggest agreement ever reached” between Russia and Ukraine can be interpreted in a few ways, depending on whether we’re talking about pre-invasion agreements or agreements during the full-scale war.
Historically, a very significant agreement was the:
* Treaty on Friendship, Cooperation, and Partnership between Ukraine and the Russian Federation (1997), also known as the “Big Treaty.” This agreement fixed the principle of strategic partnership, recognized the inviolability of existing borders, and committed both countries to respect each other’s territorial integrity. It aimed to prevent mutual invasion and declaration of war. This treaty was highly significant for establishing the foundational relationship between the two independent states after the collapse of the Soviet Union, though Russia’s actions in 2014 and 2022 fundamentally violated it.
In the context of the ongoing full-scale invasion (since 2022), the most significant agreements reached have been related to humanitarian issues:
* Large-scale prisoner and body exchanges: As of early June 2025, recent talks in Istanbul have resulted in agreements for the largest exchanges of prisoners of war (including the seriously ill, wounded, and those under 25) and the repatriation of thousands of fallen soldiers’ bodies. These agreements, while not peace treaties, are considered highly significant from a humanitarian perspective amidst the conflict.
It’s important to note that a comprehensive “peace agreement” ending the current full-scale war has not been reached. While there have been various rounds of peace talks and proposals, fundamental disagreements, particularly regarding territorial integrity and ceasefire conditions, have prevented a breakthrough.