WASHINGTON ― Former National Security Adviser Michael Flynn’s assertion of his Fifth Amendment right against self-incrimination does not apply to his businesses and documents, and he could be subject to a contempt charge if he doesn’t turn related materials over to the Senate Intelligence Committee, committee leaders said on Tuesday.

Flynn, a former lieutenant general who was fired as President Donald Trump’s national security adviser for failing to reveal contacts he had with Russia’s ambassador, refused on Monday to answer subpoenas from the Intelligence Committee, which is investigating Russian ties to the Trump campaign and interference in the 2016 election.

Committee Chairman Sen. Richard Burr (R-N.C.) and Vice Chairman Sen. Mark Warner (D-Va.) said they sent a letter to Flynn’s attorneys questioning whether their client had a right to assert the Fifth for documents.

They were also sending two new subpoenas specifically targeting Flynn’s businesses, Flynn Intel LLC, and Flynn Intel Inc., both based in Virginia.

“It is even more clear that a business does not have a right to take the Fifth. It is a corporation,” Warner told reporters.

He said that “all options” were on the table to enforce the requests.

Asked what those were, Burr said they included a contempt charge, but committee lawyers were first considering preliminary moves to obtain cooperation from Flynn.

“The end of that option is a contempt charge,” Burr said. “That’s not our preference today. We would like to hear from Gen. Flynn. We’d like to see his documents. We’d like him to tell his story because he publicly said, ‘I’ve got a story to tell.’ We’re allowing him that opportunity.”

Flynn’s firing stemmed from discussions he had with Russian Ambassador Sergey Kislyak in late December about U.S. sanctions against Russia. Flynn at first denied those talks had happened, including to Vice President Mike Pence, but was forced to resign in February after transcripts of his calls surfaced.

More seriously, Flynn failed to disclose contracts he got from foreign governments. As a recent military official, he was barred from receiving payments from foreign states unless he got permission from the Pentagon.

While Flynn accepted a number of contracts, including with Russian and Turkish entities, there is no evidence he ever sought permission for them, according to the Department of Defense. Flynn also allegedly did not disclose contracts as required to the federal government when he was vetted to be Trump’s top national security aide.

Intelligence officials warned last fall that Russia was taking unprecedented steps to interfere with the U.S. election. The Senate Intelligence Committee is trying to ascertain exactly what sort of communications the Trump campaign may have had with agents of Russian President Vladimir Putin. The FBI is also investigating.

Last week, the Department of Justice named former FBI Director Robert Mueller as a special counsel to look into Trump-Russia ties after Trump fired FBI Director James Comey. Trump said he dismissed Comey over his handling of the Hillary Clinton email investigation, although the president also suggested that Comey’s probe of his own administration was weighing on his mind.