Vietnam is still not accepting deportees, as a categorical matter, except some recent travelers from Vietnam who have valid passports.  The United States cannot currently remove Vietnamese nationals who came here as refugees in the 1970s-1990s, so they have Zadvydas claims. The United States has been attempting to negotiate a repatriation agreement with Vietnam for years, without success. Proposed legislation seeks to reverse Zadvydas.  If one of these bills passes, post-order indefinite detainees must again litigate the constitutionality of indefinite detention in the United States Supreme Court.
Thanks to Jay W. Stansell.