For a specific example, Vietnam refuses to take back their nationals who entered after 12 July 1995. We recently had a case regarding Viet national in the US illegally who, upon serving that sentence, was released among the US public because he had originally entered the US illegally before that 1995 date, and Vietnam refused to allow him back in.

He went on to commit another homicide this year.

- The country is too slow in taking back people, which is entirely possible when the plan to deport 3 million people is implemented.

- Especially for "illegal immigrants", it's sometimes hard to pinpoint their actual nationality (and they might not be honest about it for whatever reasons). So they claim to be from India, but the Indian Embassy claims that they're definitely not Indian but given their accent may be from Sri Lanka (and so refuse to take them back). Sri Lanka doesn't want anything to do with that person either. Now what?

Neither of these need to happen, but these are issues completely outside the control of law-abiding visa holders that may soon be hanging over their heads.