The GDR was a one-party state[4] but other institutional popular front parties were permitted to exist in alliance with the SED, these parties being the Christian Democratic Union, the Liberal Democratic Party, the Democratic Farmers' Party, and the National Democratic Party. The SED made the teaching of Marxism-Leninism and the Russian language compulsory in schools.[5] In the 1980s, the SED rejected the liberalisation policies of Soviet leader Mikhail Gorbachev, such as perestroika and glasnost, which would lead to the GDR's isolation from the restructuring USSR and the party's downfall in the autumn of 1989.