The occupation of the Baltic states refers to the military occupation of the three Baltic states—Estonia, Latvia and Lithuania—by the Soviet Union under the auspices of the Molotov–Ribbentrop Pact on 14 June 1940 followed by their incorporation into the USSR as constituent republics, unrecognised internationally by most western opponents of the Soviet Union. On 22 June 1941 Nazi Germany attacked the USSR and within weeks occupied the Baltic territories. In July 1941, the Baltic territory was incorporated into the Reichskommissariat Ostland of the Third Reich. As a result of the Baltic Offensive of 1944, the Soviet Union recaptured most of the Baltic states and trapped the remaining German forces in the Courland pocket until their formal surrender in May 1945. The Soviet "annexation occupation" (Annexionsbesetzung or occupation sui generis) of the Baltic states lasted until August 1991, when the Baltic states regained independence.