In Greece, civil war broke out in 1946 between Anglo-American-supported royalist forces and communist-led forces, with the royalist forces emerging as the victors. The US launched a massive programme of military and economic aid to Greece and to neighbouring Turkey, arising from a fear that the Soviet Union stood on the verge of breaking through the NATO defence line to the oil-rich Middle East. On 12 March 1947, to gain Congressional support for the aid, President Truman described the aid as promoting democracy in defence of the "free world", a principle that became known as the Truman Doctrine.