House Intelligence Committee Chairman Devin Nunes (R-CA) said Tuesday that those who leaked the contents of former National Security Adviser Michael Flynn’s phone calls “belong in jail.”

“That’s nine leakers that all belong in jail,” Nunes said. “Those nine people broke the law, clearly, by leaking classified information to anybody.”

Flynn resigned late Monday night, after a Washington Post report on Feb. 9 said he had privately discussed U.S. sanctions against Russia with a Russian ambassador during phone calls in December — despite assertions by Trump officials, including the vice president, that he had never done so.

The Post’s report cited nine anonymous current and former officials “who were in senior positions at multiple agencies” who “had access to reports from U.S. intelligence and law enforcement agencies that routinely monitor the communications of Russian diplomats.”

“All of those officials said Flynn’s references to the election-related sanctions were explicit,” the report said.

Nunes said he also wanted to know how U.S. intelligence agencies were wiretapping Flynn’s calls, which he said may also have been illegal.

The chairman said there are only two ways that intelligence agencies can listen in on an American’s phone call — after obtaining a warrant, or inadvertently, such as in the case of Flynn speaking with a foreign official being spied on, which the report suggests was the case.

Nunes said “it’s pretty clear” that there was no warrant.

“It’s pretty clear that’s not the case,” he said. “I’m pretty sure the FBI didn’t have a warrant on Michael Flynn … To listen to an American’s phone call you would have to go to a court, there’d be all that paperwork there. So I’m guessing that doesn’t exist.”

In case Flynn was speaking to a foreign official — Russian Ambassador Sergey Kislyak in this case — Nunes said there should have been a process to mask Flynn’s identity.

“Unless it’s a high-level national security issue, and then someone would have to unmask the name, someone at the highest levels, they’d have to unmask that name,” Nunes said. “It’s a very high threshold to unmask an American citizen’s name, that’s a very high threshold, almost unprecedented. And if you were going to unmask it, it seems like you would immediately go get a warrant.”

“If they did that, how does all that get out to the public which is another leak of classified information,” he added. “Whoever did it, it’s illegal.”

A Wall Street Journal editorial on Tuesday also questioned whether spies listening to Flynn broke the law.

The editorial said U.S. intelligence services routinely get orders from the Foreign Intelligence Surveillance Court to monitor foreign officials, but are supposed to use “minimization procedures” that don’t let them listen to the communications of an American.

“That is, they are supposed to protect the identity and speech of innocent Americans. Yet the Washington Post, which broke the story, says it spoke to multiple U.S. officials claiming to know what Mr. Flynn said on that call,” the Journal said.

“The questions someone in the White House should ask the National Security Agency is why it didn’t use minimization procedures to protect Mr. Flynn? Or did it also have a court order to listen to Mr. Flynn, and how did it justify that judicial request?” it added.

“If Mr. Flynn was under U.S. intelligence surveillance, then Mr. Trump should know why, and at this point so should the American public. Maybe there’s an innocent explanation, but the Trump White House needs to know what’s going on with Mr. Flynn and U.S. spies,” it said.

Nunes said he is seeking more information from the FBI on what happened.

“There’s nothing to investigate until I know what happened,” he said.