Believe it or not.
The US left behind every POW captured in Laos and Cambodia, approximately the same number as were captured in North and South Vietnam.
In an agreement negotiated by Kissinger, they were to be repatriated when the US contributed to the reconstruction of North Vietnam. Watergate and the Nixon resignation, coupled with US weariness with the situation prevented the funds from being allocated, and the prisoners have been kept over there.
