Between 1970 and 1975, Sihanouk took up residence in state guesthouses at Beijing and Pyongyang, courtesy of the Chinese and North Korean governments, respectively. In February 1973, Sihanouk traveled to Hanoi, where he started on a long journey with Khieu Samphan and other Khmer Rouge leaders. The convoy proceeded along the Ho Chi Minh trail and reached the Cambodian border at Stung Treng Province the following month. From there, they traveled across the provinces of Stung Treng, Preah Vihear, and Siem Reap. Throughout this entire leg of the journey, Sihanouk faced constant bombardment from American planes participating in Operation Freedom Deal. At Siem Reap, Sihanouk visited the temples of Angkor Wat, Banteay Srei, and Bayon. In August 1973, Sirik Matak wrote an open letter calling on Sihanouk to bring the Cambodian Civil War to an end and suggesting the possibility of his return to the country. When the letter reached Sihanouk, he angrily rejected Sirik Matak's entreaties.