In the wake of Michael Flynn’s resignation as national security adviser, President Trump and Republican allies on Capitol Hill are turning their attention to the potentially “illegal” leaks that revealed Flynn's politically fatal discussions with a Russian diplomat and other sensitive details from inside the administration.

Fox News first reported Monday night that House Intelligence Committee Chairman Devin Nunes, R-Calif., wants the FBI to conduct an assessment of recent media leaks.

TOP REPUBLICAN WANTS FBI REVIEW ON TRUMP LEAKS

The president, after accepting Flynn’s resignation overnight, tweeted Tuesday morning that, “The real story here is why are there so many illegal leaks coming out of Washington?”

Flynn echoed that point. Asked Tuesday morning whether the leaks were targeted, coordinated and possibly a violation of the law, Flynn told Fox News: “Yes, yes and yes.”

Flynn resigned following reports that he had spoken with the Russian ambassador about sanctions, after having apparently given Vice President Pence “incomplete information” on the issue. Pence, based on that information, previously had claimed Flynn did not discuss sanctions with the Russian official.

Such conversations would breach diplomatic protocol and possibly violate the Logan Act, a law aimed at keeping private citizens from conducting U.S. diplomacy. The Justice Department also had warned the White House late last month that Flynn could be in a compromised position because of contradictions between his public depictions of the calls and what intelligence officials knew to be true based on routine recordings of communications with foreign officials who are in the U.S.

Yet the leak itself is raising serious questions -- because when the intelligence community captures phone calls of an American inside the U.S., even if the discussion involves a foreign national (in this case an ambassador), steps must be taken to shield the American caller's identity.

Recent leaks also have revealed reported details from phone calls between Trump and the leaders of Australia and Mexico and from the intelligence community investigation into Russian interference in the U.S. presidential campaign.

"If [the Flynn conversation] was picked up inadvertently, then that would have had to have been approved by someone in the last administration to actually unmask his name so that the FBI or intelligence officials knew who it was on the other end of the phone talking to the Russian ambassador," Nunes told Fox News. "If, in fact, the press reports are right, someone made the decision to deliberately listen to General Flynn's phone calls and that is, I think, unprecedented, unwarranted and flat-out wrong."

Nunes said he is going to “be asking the FBI to do an assessment of this to tell us what's going on here because we cannot continue to have these leaks as a government."

Senate homeland security committee Chairman Ron Johnson, R-Wis., told Fox News that “somebody in the nebulous intelligence community” would have had access to the Flynn discussions.

“Who tapped the phones, who was listening to it, who leaked it? I think those are legitimate questions to ask,” he told Fox News on Tuesday. “Leaks of this nature are incredibly damaging to America … and we need to look into it.”

A congressional source told Fox News they believe the intelligence was known to a small circle of Obama administration officials and appointees at the end of last year, including some working within the intelligence community -- and the leaks were targeted and coordinated to undermine the administration.

House Democrats, meanwhile, want to know more about the nature of Flynn’s contact with Russia.

"… Flynn's departure does not end questions over his contacts with the Russians, which have been alleged to have begun well before December 29,” Rep. Adam Schiff, D-Calif., top Democrat on the House intelligence committee, said in a statement. “These alleged contacts and any others the Trump campaign may have had with the Kremlin are the subject of the House Intelligence Committee's ongoing investigation. Moreover, the Trump administration has yet to be forthcoming about who was aware of Flynn's conversations with the ambassador and whether he was acting on the instructions of the president or any other officials, or with their knowledge."

Fox News’ Catherine Herridge and The Associated Press contributed to this report.