The significance of the War Powers Act in the U.S. is that it limits the president's ability to engage in military actions without congressional approval. Enacted in 1973 in response to the Vietnam War, the Act emphasized the need for Congressional oversight regarding the deployment of U.S. armed forces. It requires the president to notify Congress within 48 hours of committing troops and restricts military engagement to 60 days without a formal declaration of war. The War Powers Act reflects the ongoing tension between executive and legislative powers in matters of war and peace, aiming to prevent unilateral military actions by the president.