The Cold War is generally considered to have ended in 1991, marked by the dissolution of the Soviet Union. The period from 1985 to 1991 saw significant reforms within the Soviet Union under Mikhail Gorbachev, including economic restructuring (perestroika) and political liberalization (glasnost), which contributed to easing geopolitical tensions between the Soviet-led bloc and the United States-led bloc. Key events signaling the end of the Cold War included the withdrawal of Soviet forces from Eastern Europe and Afghanistan, arms control agreements such as the 1987 Intermediate Nuclear Forces Treaty, and the collapse of communist regimes in Eastern Europe. A symbolic moment often noted was the Malta Summit in 1989, where U.S. President George H. W. Bush and Gorbachev declared the Cold War over. However, the definitive end came with the formal dissolution of the Soviet Union in December 1991, which effectively ended the bipolar global rivalry that had defined the Cold War era. Following this, the United States emerged as the sole superpower globally.