Prior to 1991, Ukraine was part of the Soviet Union and had Soviet nuclear weapons in its territory.
On December 1, 1991, Ukraine, the second most powerful republic in the Soviet Union (USSR), voted overwhelmingly for independence, which ended any realistic chance of the Soviet Union staying together even on a limited scale. More than 90% of the electorate expressed their support for Ukraine's declaration of independence, and they elected the chairman of the parliament, Leonid Kravchuk as the first president of the country. At the meetings in Brest, Belarus on December 8, and in Alma Ata on December 21, the leaders of Belarus, Russia, and Ukraine formally dissolved the Soviet Union and formed the Commonwealth of Independent States (CIS).
After the dissolution of the Soviet Union, Ukraine held about one third of the Soviet nuclear arsenal, the third largest in the world at the time, as well as significant means of its design and production. 130 UR-100N intercontinental ballistic missiles (ICBM) with six warheads each, 46 RT-23 Molodets ICBMs with ten warheads apiece, as well as 33 heavy bombers, totaling approximately 1,700 warheads remained on Ukrainian territory. While Ukraine had physical control of the weapons, it did not have operational control, as they were dependent on Russian-controlled electronic Permissive Action Links and the Russian command and control system. In 1994 Ukraine agreed to destroy the weapons, and to join the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).