Answer:
communism
Step-by-step explanation:
The Truman Doctrine is an expression that designates a set of political and economic measures taken after March 1947, the date on which President Harry Truman delivered a harsh speech against the threat of communism. In this vision, the US is committed to defending the world of the Soviets.
This may be considered the harbinger of the Cold War. After the Second World War, two economic powers emerged. The US, capitalist and the USSR, socialist. These powers would dispute the hegemony of the world economic system. That is why Trumam saw the USSR as a threat to the world.