The War Powers Resolution of 1973 resulted from a constitutional battle between the legislative and executive branches in how the United States should commit to military conflicts. Congress traditionally held the power of declaring war, but it has not declared war since December 1941, when the United States entered World War II. As the definitions of war and military actions have blurred, Congress has ceded conflict-entry power in deference of the executive's commander in chief powers. The War Powers Resolution allows a President 60 days with a 30 day withdrawal period to conduct military actions without a congressional declaration of war or authorization of force. Its importance is emphasized by its recent invocations and in the constantly changing positions of the executive and legislative in their war and authorization powers.