The whole of Lithuania was annexed by the Soviet Union on 3 August 1940 following a June ultimatum from the Soviets demanding, among other things, that unspecified numbers of Red Army soldiers be allowed to enter the country for the purpose of helping to form a more pro-Soviet government. After the ultimatum was issued and Lithuania further occupied, a Soviet government was installed with Vilnius as the capital of the newly created Lithuanian SSR. Between 20,000 and 30,000 of the city's inhabitants were subsequently arrested by the NKVD and sent to gulags in the far eastern areas of the Soviet Union.