In 1918 the Slovaks joined the closely related Czechs to form Czechoslovakia. Following the chaos of World War II, Czechoslovakia became a Communist nation within Soviet-ruled Eastern Europe. Soviet influence collapsed in 1989 and Czechoslovakia once more became free. The Slovaks and the Czechs agreed to separate peacefully on 1 January 1993. Slovakia joined both NATO and the EU in the spring of 2004.