 The weakness of the Red Army was partly consequence of the Great Purge (1936–1938) of senior officers and career soldiers whom Stalin considered politically unreliable.Strategically, the Wehrmacht's extensive and effective attack threatened the territorial integrity of the Soviet Union, and the political integrity of Stalin's model of a Marxist–Leninist state, when the Nazis were initially welcomed as liberators by the anti-communist and nationalist populations in the Byelorussian Soviet Socialist Republic, the Georgian Soviet Socialist Republic and the Ukrainian Soviet Socialist Republic.The anti-Soviet nationalists' collaboration with the Nazi's lasted until the "Schutzstaffel" and the "Einsatzgruppen" began their "Lebensraum" killings of the Jewish populations, the local communists, the civil and community leaders—the Holocaust meant to realise the Nazi German colonisation of Bolshevik Russia.