With the 1940 election looming, Menzies lost his Chief of the General Staff and three loyal ministers in a Royal Australian Airforce crash at Canberra airport. In response, Menzies recalled Harold Holt, a minister who had resigned to join the army. The Labor Party meanwhile experienced a split along pro and anti Communist lines over policy towards the Soviet Union for its co-operation with Nazi Germany in the invasion of Poland. The Communist Party of Australia (CPA) opposed and sought to disrupt Australia's "imperialist" war effort against Nazism in the early stages of the War. Menzies banned the CPA after the fall of France in 1940, but by 1941 Stalin was forced to join the allied cause when Hitler reneged on the Pact and invaded the USSR. The USSR came to bear the brunt of the carnage of Hitler's war machine and the Communist Party in Australia lost its early war stigma as a result. In Menzies later term of office, anti-communism became an important plank of his foreign policy.