In January 1962, during the beginning of the Laotian Civil War, Prime Minister Souvanna Phouma struck a foreign aid pact with the People's Republic of China (PRC). The Communist Chinese would build roads in northwestern Laos despite the ongoing Laotian Civil War. As part of this project, in the wake of the defeat at Nam Bac on 14 January 1968, Chinese engineers began building Route 46 from Yunnan Province south down the Nam Beng Valley towards Pakbeng, which was located on the Mekong River. As the road construction neared the Thai border, and was guarded by Chinese troops and antiaircraft guns, the Royal Thai Government (RTG) became concerned about the possibility of both a Chinese invasion and Chinese support for the Communist Party of Thailand.