I have encountered numerous US guys in Vietnam who skipped over there to stay to avoid paying Alimony and Child Support for kids they never see.

Even being a U.S. citizen is not, however, enough in some cases. Under a program called “Passport Denial,” authorized by a 1997 amendment to a law called the Personal Responsibility and Work Opportunity Reconciliation Act (PRWORA), any person who owes child support in an amount greater than $2,500 will be denied a U.S. passport until the matter is cleared up. (At one time, the threshold was $5,000, but it was lowered to $2,500 in 2007.)

What’s more, if the person already has a passport, the U.S. government can revoke, restrict, or limit its use. (As a practical matter, however, they are currently unable to do that without having physical access to the person’s passport, such as during a renewal.)