<P> In response to the anti-war movement , the U.S. Congress passed the Case -- Church Amendment to prohibit further U.S. military intervention in Vietnam in June 1973 and reduced aid to South Vietnam in August 1974 . With U.S. bombing ended , communist logistical preparations could be accelerated . An oil pipeline was built from North Vietnam to Việt Cộng headquarters in Lộc Ninh , about 75 miles northwest of Saigon . ( COSVN was moved back to South Vietnam following the Easter Offensive . ) The Ho Chi Minh Trail , beginning as a series of treacherous mountain tracks at the start of the war , was upgraded throughout the war , first into a road network driveable by trucks in the dry season , and finally , into paved , all - weather roads that could be used year - round , even during the monsoon . Between the beginning of 1974 and April 1975 , with now - excellent roads and no fear of air interdiction , the communists delivered nearly 365,000 tons of war matériel to battlefields , 2.6 times the total for the previous 13 years . </P>
what name is given to the series of roads used by communist forces during the vietnam war
The Ho Chi Minh Trail