 While Sihanouk was abroad in France for a rest cure in January 1970 , government @-@ sponsored anti @-@ Vietnamese demonstrations were held throughout Cambodia . Continued unrest spurred Prime Minister / Defense Minister Lon Nol to close the port of Sihanoukville to communist supplies and to issue an ultimatum on 12 March to the North Vietnamese to withdraw their forces from Cambodia within 72 hours . The prince , outraged that his " <unk> <unk> " with the communists had been disturbed , immediately arranged for a trip to Moscow and Beijing in an attempt to gain their agreement to apply pressure on Hanoi to <unk> its forces in Cambodia . 
