Operation Market Time
The Navy established Operation Market Time (March 1965-1972) to prevent North Vietnamese ships from supplying enemy forces in South Vietnam by sea. The Coastal Surveillance Force (Task Force 115) used a system of three barriers to patrol the South Vietnamese coast. Patrol aircraft covered the outermost barrier to identify, photograph, and report suspicious vessels and U.S. Coast Guard cutters stopped and searched cargo vessels in the middle barrier forty miles off the coast. The South Vietnamese Navy, the Junk Force, and U.S. Navy Patrol Craft Fast (PCF( Swift boats cruised the coastal waters of the inner barriers. By 1968, these forces stopped virtually all seaborne infiltration from North Vietnam to South Vietnam. The blockade forced the North Vietnamese to rely on the Ho Chi Minh Trail and the Cambodian port of Sihanoukville to transport supplies to the Viet Cong.