How did President Truman exercise increased presidential powers while in office?

President Harry S. Truman exercised increased presidential powers through several key actions, particularly in foreign policy and national security. Notably, he made the controversial decision to use atomic bombs on Japan without congressional approval, demonstrating his authority as Commander-in-Chief. Additionally, Truman implemented the Truman Doctrine and Marshall Plan, which expanded U.S. involvement in global affairs and set a precedent for executive-led foreign policy initiatives. His establishment of the National Security Council and the Central Intelligence Agency further solidified the presidency's role in managing national security.