Wikipedia

The Budapest Memorandum on Security Assurances comprises three substantially identical political agreements signed at the OSCE conference in Budapest, Hungary, on 5 December 1994, to provide security assurances by its signatories relating to the accession of Belarus, Kazakhstan and Ukraine to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). The three memoranda were originally signed by three nuclear powers: Russia, the United States and the United Kingdom. China and France gave somewhat weaker individual assurances in separate documents. The memoranda, signed in Patria Hall at the Budapest Convention Center with U.S. Ambassador Donald M. Blinken amongst others in attendance, prohibited Russia, the United States and the United Kingdom from threatening or using military force or economic coercion against Ukraine, Belarus, and Kazakhstan, "except in self-defence or otherwise in accordance with the Charter of the United Nations."...