Vice Admiral Elmo R. Zumwalt, Jr., Commander, U.S. Naval Forces in Vietnam, decided to blockade waterways from the Gulf of Siam to north of Saigon. The U.S. launched Operation SEALORDS (Southeast Asia Lake, Ocean, River, Delta Strategy) in November 1968 to keep the enemy on the defensive after their heavy losses from the Tet Offensive. The Navy took the lead to cut off supply routes from Cambodia and to take out enemy bases in the Mekong Delta. Patrol Craft Fast (PCF), also known as Swift boats, conducted fast raids into coastal waterways and took over patrol duties on the larger rivers in the delta, allowing PBRs to patrol canals and smaller rivers. Ending in 1971, SEALORDS’ success helped prepare Vietnamese allies for the eventual turnover of operations as U.S. forces withdrew.