“If Trump thinks he knows the name, he can come out and say it, and he’s probably as protected as anyone is,” said Robert Litt, former general counsel for the Office of the Director of National Intelligence under President Obama.

Litt and several other legal experts who talked to NPR said Trump uttering or tweeting the name could in theory trigger an article of impeachment for retaliating against a whistleblower, but it would not run afoul of any federal criminal statutes.

Similarly if a news outlet, member of Congress or member of the public outed the whistleblower, legal experts said, no criminal law would be violated.

“There is no overarching protection for the identity of the whistleblower under federal law,” said Dan Meyer, a lawyer and the former executive director of the intelligence community whistleblower program. “Congress has never provided that protection.”