The last quarter of the twentieth century saw the end of the
Cold War, the collapse of Communist rule in Eastern Europe, and
economic unification of Western Europe. American popular culture
had a global influence, as did the use of terrorism as a
political tool. Section 1 Decline of the Soviet Union The 1970s
saw a relaxation of Cold War tensions, known as détente. The
1979 Soviet invasion of Afghanistan brought back old fears of
Soviet expansion. Tensions heightened further when Ronald Reagan
called the Soviet Union an "evil empire" and began a new arms
race. Leonid Brezhnev, the Soviet leader of the 1970s, had been
uninterested in reform. However, Mikhail Gorbachev, who came to
power in 1985, saw the need for radical change to save an ailing
economy. Gorbachev coupled his domestic reform plans with an
easing of Communist party control over the republics of the
Soviet Union. Agreements with the United States sharply reduced
nuclear arms stockpiles. Gorbachev's reforms led to the break-up
of the Soviet Union