This recently declassified study from 1978 details on Air Force participation-in the last tempestuous year of US involvement in the war in Vietnam when, after the great majority of US forces had been withdrawn, Hanoi launched its smashing Easter offensive. This study relates how air, as almost the sole remaining US weapon, played a complex and varied role. This consisted not only of its key part in the military operations which turned back the enemy offensive, but also of its influence on the negotiating process and its exercise of a "persuasion" role for US diplomacy .