<P> The oil price shock of October 1973 following the Yom Kippur War in Egypt caused significant damage to the South Vietnamese economy . The Viet Cong resumed offensive operations when the dry season began and by January 1974 it had recaptured the territory it lost during the previous dry season . After two clashes that left 55 South Vietnamese soldiers dead, President Thieu announced on 4 January that the war had restarted and that the Paris Peace Accord was no longer in effect . There had been over 25,000 South Vietnamese casualties during the ceasefire period . </P> <P> Gerald Ford took over as U.S. president on 9 August 1974 after President Nixon resigned due to the Watergate scandal . At this time, Congress cut financial aid to South Vietnam from $1 billion a year to $700 million . The U.S. midterm elections in 1974 brought in a new Congress dominated by Democrats who were even more determined to confront the president on the war . Congress immediately voted in restrictions on funding and military activities to be phased in through 1975 and to culminate in a total cutoff of funding in 1976 . </P> <P> The success of the 1973--74 dry season offensive inspired Trà to return to Hanoi in October 1974 and plead for a larger offensive in the next dry season . This time, Trà could travel on a drivable highway with regular fueling stops, a vast change from the days when the Ho Chi Minh trail was a dangerous mountain trek . Giáp, the North Vietnamese defense minister, was reluctant to approve Trà's plan . A larger offensive might provoke a U.S. reaction and interfere with the big push planned for 1976 . Trà appealed over Giáp's head to first secretary Lê Duẩn, who approved of the operation . </P> <P> Trà's plan called for a limited offensive from Cambodia into Phước Long Province . The strike was designed to solve local logistical problems, gauge the reaction of South Vietnamese forces, and determine whether U.S. would return to the fray . </P>

All us troops had left south vietnam by