July 1967 and August 1969. The North Vietnamese were forced to use the Ho Chi Minh trail through Laos or the neutral port of Sihanoukville in Cambodia to ship supplies to the Viet Cong. With the closing of the port at Sihanoukville to Communist shipping in August 1969, attempted North Vietnamese trawler traffic into South Vietnam resumed. Of 15 trawlers detected by Market Time assets from August 1969 to late 1970, one was sunk, 13 were turned back and only one got through. In 1970, ten out of eleven trawlers were either sunk or were turned back. Notes Footnotes Citations References cited United States Coast Guard Conflicts in 1968 1968 in Vietnam Naval battles of the Vietnam War History of Vietnam (1945–present) Naval battles of the Vietnam War involving the United States Battles involving Vietnam Battles and operations of the Vietnam War in 1968 March 1968 events in Asia