At the Strategic Arms Reduction Treaty (START) in 1991, the USA and Soviet Union agreed to reduce nuclear warheads by about a third, with an additional undertaking to reduce them further.
Gorbachev tried to save Soviet communism by issuing a new constitution in the Soviet Union that would have given Soviet republics, such as Estonia, Latvia, Lithuania and Ukraine, more independence.
Many Soviet states seceded (broke away) from the Soviet Union and became independent states, including Ukraine, Estonia, Latvia and Lithuania, as well as Asian Republics, such as Kazakhstan.