What 1967 US operation was the largest US airborne operation of the Vietnam War?

The 1967 US operation that was the largest US airborne operation of the Vietnam War was Operation Junction City.

Launched on February 22, 1967, Junction City was an 82-day search-and-destroy campaign in War Zone C, north of Saigon near the Cambodian border. Its main objectives were to disrupt Viet Cong control of the area and locate or destroy COSVN, the Communist headquarters for military and political activity in South Vietnam. More than 30,000 American and South Vietnamese troops took part.

The operation is especially notable for the combat jump by the 173rd Airborne Brigade. On the opening day, 845 soldiers of the 2nd Battalion, 503rd Infantry Regiment, parachuted from 13 C-130 aircraft—the only conventional US combat parachute assault of the Vietnam War. Most of the operation, however, used helicopters, infantry, armor and artillery rather than parachutes.

A common mix-up is Operation Cedar Falls, which immediately preceded Junction City and was the largest American ground operation to that point. Cedar Falls targeted the nearby Iron Triangle; Junction City then extended the offensive into War Zone C.