Now, their long-standing feud has escalated after Trump threatened to revoke the comedian's U.S. citizenship months after she fled to Ireland.

President Donald Trump’s recent threat that he was considering revoking Rosie O’Donnell’s citizenship says a lot about how the president intends to govern — and it’s “terrifying,” experts say.

Trump appears to view both free speech and U.S. citizenship as conditional, things he can revoke based on his own whims.