Treaty of Warsaw
The easing of tensions with the East envisioned by "Ostpolitik" necessarily began with the Soviet Union, the only Eastern Bloc state with which the Federal Republic had formal diplomatic ties (despite the aforementioned Hallstein Doctrine). In 1970 Brandt signed the Treaty of Moscow, renouncing the use of force and recognizing the current European borders. Later that year, Brandt signed the Treaty of Warsaw, in the process formally recognizing the People's Republic of Poland. The Treaty of Warsaw essentially repeated the Moscow treaty, and in particular reiterated the Federal Republic's recognition of the Oder–Neisse line. Treaties with other Eastern European countries followed.