Before the Germans decided to invade the Soviet Union in June 1941, relations remained strained, as the Soviet invasion of Finland, Molotov–Ribbentrop Pact, Soviet invasion of the Baltic states and the Soviet invasion of Poland stirred, which resulted in Soviet Union's expulsion from the League of Nations. Come the invasion of 1941, the Soviet Union entered a Mutual Assistance Treaty with the United Kingdom, and received aid from the American Lend-Lease program, relieving American-Soviet tensions, and bringing together former enemies in the fight against Nazi Germany and the Axis powers.