The relationship between the two countries became strained thereafter, and Cambodia gave refuge to Vietnamese military personnel involved in attempts to overthrow Diệm. Colonel Nguyễn Chánh Thi and Lieutenant Colonel Vương Văn Đông were given immediate refuge after a failed coup in November 1960, and Republic of Vietnam Air Force pilot Lieutenant Nguyễn Văn Cử was accorded the same treatment after he failed to kill the Ngôs in February 1962.