How the Vietnam war first allowed an expansion of presidential power and later caused power to be limited ? – History, Politics & SocietyReport
Nixon’s invasion (incursion) of Cambodia in ’70 triggered the limitations. Unfortunately, this caused a disaster when the Laos invasion occurred the following year (1971-Operation Lam Son 719).
In responding to a reported attack on U.S. warships, Congress passed a resolution giving President Lyndon Johnson authority to take “all necessary steps,” including the use of American forces, in Vietnam. After the war dragged on for years, Congress decided that Johnson and President Richard Nixon had abused their war powers and passed a law to limit the president’s use of forces in combat without congressional approval.