Who said that it must be the policy of the US to support free people?

The phrase about the U.S. supporting free people was famously articulated by President Harry S. Truman in his Truman Doctrine speech on March 12, 1947. He emphasized the importance of supporting nations resisting subjugation by armed minorities or outside pressures, particularly in the context of the Cold War. This doctrine was a pivotal moment in U.S. foreign policy, marking a commitment to counter Soviet influence globally.