In 1996 Ieng Sary, the regime's former Deputy Premier, was the first major cadre to defect to the government--strengthening Hun Sen's hand in his power struggle with then co-Premier Norodom Ranariddh--and was granted an official amnesty in return.
Testimony from former Czech Major General Jan Sejna, the most senior Warsaw Pact officer ever to defect to the United States, was cited to the effect that a substantial number of U.S. servicemen were secretly transferred from Vietnam to Russia via Czechoslovakia for heinous experiments with chemical, biological, radiological warfare and mind-altering drugs.