How did the Truman doctrine and marshall plan cause the US to change its foreign policy goal of isolationism?

The Truman Doctrine and the Marshall Plan marked a significant shift in U.S. foreign policy from isolationism to active engagement in global affairs. The Truman Doctrine established a commitment to contain the spread of communism, signaling that the U.S. would intervene in international conflicts to support free nations. Meanwhile, the Marshall Plan provided substantial economic aid to rebuild European economies post-World War II, fostering stability and preventing the rise of communist influence. Together, these initiatives reflected a strategic decision to take a proactive role in shaping the international order and promoting democracy.