He said their political activities were motivated by sincere conviction that they had uncovered wrongdoing that should be investigated.

“We’re American citizens, we love our country, we love our president,”he said.

The men make for unlikely back-channel diplomats. Parnas, 47, is a former stockbroker with a history of unpaid debts, including half a million dollars owed to a Hollywood movie investor. Fruman, 53, has spent much of his career in Ukraine, and has ties to a powerful local businessman reputed to be in the inner circle of one of the country’s most infamous mafia groups.

Giuliani and Fruman didn’t respond to multiple requests for interviews or to written questions. The White House did not respond to a request for comment.

Kenneth McCallion, an ex-federal prosecutor who has represented former Ukrainian Prime Minister Yuliya Tymoshenko in U.S. court, said that Parnas and Fruman were “playing with fire” by lobbying in the United States and Ukraine without registering as foreign agents.

“Trump has either authorized Giuliani to engage in private diplomacy and deal-making, or even worse, remains silent while Giuliani and his dodgy band of soldiers of fortune engage in activities that severely undermine U.S. credibility and are contrary to fundamental U.S. interests,” McCallion said.