During the Vietnam War (1954-75), as part of the strategic bombing campaign known as Operation Rolling Thunder, U.S. military aircraft attacked targets throughout North Vietnam from March 1965 to October 1968. This massive bombardment was intended to put military pressure on North Vietnam’s Communist leaders and reduce their capacity to wage war against the U.S.-supported government of South Vietnam. Operation Rolling Thunder marked the first sustained American assault on North Vietnamese territory and thus represented a major expansion of U.S. involvement in the Vietnam War. Historians differ in their assessments of the strategic value of Operation Rolling Thunder. Some claim that the bombing campaign came close to crippling North Vietnam’s capacity to wage war, while others contend the campaign’s effectiveness was limited.