There are two ways the USA could strip them of their citizenship, that I'm aware of:The article says all of them were naturalized American citizens. I wonder what happened to the kids' American citizenship. Were they stripped of it?
1. The Department of State could move to revoke their citizenship and/or invalidate their naturalization as fraudulent. If the children chose to redress this decision in the courts, the U.S. Government would certainly not win, as the children, themselves, did not commit fraud to obtain citizenship, nor have they, themselves, committed treason, nor an expatriating act, nor a potentially expatriating act with the intent to relinquish U.S. citizenship, nor did they fight against U.S. troops on a battlefield -- these are the only legal grounds for revocation of citizenship. Of course, if they didn't fight this in the courts, or if they failed to see the court cases through to a final verdict (it could cost over $250,000 and take 20 years for the courts to reach a final verdict), they would have lost their citizenship. The U.S. Government relies on most citizens not having the funds, competent legal counsel, and adequate knowledge of their legal remedies to successfully pursue a tort action.
2. Border guards at a port of entry could have seized their citizenship documents and threatened them with decades in prison if they didn't immediately sign documents renouncing their U.S. citizenship as obtained fraudulently and "voluntarily" gift their citizenship documents to CBP. (This is reported to have happened thousands of times, especially at Mexican border crossings.)