My rewording 1:
The Truman Doctrine was a leading force in pushing America to the containment of communism from anywhere it was found. In truth, this new approach would cause the United States to support non-communist governments throughout the world.
My rewording 2:
On March 12, 1947, Harry Truman, the president of the United States at the time, would coax Congress to support the Truman Doctrine, which would give military and financial assistance to Greece and Turkey in order to prevent Soviet domination.
How I'd mix them:
On March 12, 1947, President Harry Truman would coax Congress to support the Truman Doctrine, which would provide Greece and Turkey the military and financial aid that it needs to prevent Soviet domination. In fact, the Truman Doctrine would end up playing a large role in containing the spread of communism in more places than originally intended; the doctrine would eventually cause the United States to support and provide for non-communist governments throughout the world.