Committee Chairman Sen. Richard Burr, R-N.C., and Vice Chairman Sen. Mark Warner, D-Va., told reporters on Tuesday that committee members sent the subpoenas to Flynn Intel LLC and Flynn Intel, Inc. with a specific list of documents they seek, though the senators did not disclose to what those documents related.
Flynn recently invoked his Fifth Amendment right to deny Senate subpoena requests related to its investigation into Russia's meddling in the 2016 U.S. presidential election.
"While we disagree with Gen. Flynn's lawyer's interpretation of taking the Fifth, it is even more clear that a business does not have a right to take the Fifth if it's a corporation," Warner said on Tuesday.
Burr said "everything is on the table" if Flynn does not respond to the subpoena.
"If in fact there's not a response, we'll seek additional counsel advice on how to proceed forward," Burr said. "At the end of that option is a contempt charge, and I've said that everything is on the table."
The subpoena delivery follows recent activity concerning the investigation into Russia.
On Monday, Rep. Elijah Cummings, D-Md., said documents already in the House Oversight Committee's possession appear to indicate that Flynn may have lied to investigators last year when they were conducting a background check for his top-level security clearance.
On May 9, Trump fired FBI Director James Comey, who was leading the federal investigation into Russia's meddling and connections with Trump's associates. Some high-ranking Democrats accused Trump of engaging in a coverup.
Trump said he fired Comey following "clear" advice from Attorney General Sessions and Deputy Attorney General Rod Rosenstein, who, among other reasons, cited Comey's handling of the investigation into Hillary Clinton's emails as the reason he should be dismissed.
Federal prosecutors also on May 9 issued subpoenas to associates of Flynn as part of the FBI's investigation.
Flynn was Trump's first appointment as national security adviser. He was forced to resign after 24 days when information surfaced that he misled Vice President Mike Pence about his meetings with the Russian ambassador to the United States.
Flynn also previously served as the head of the Defense Intelligence Agency until he was forced out in 2014 due to internal disagreements.
Flynn's involvement with Russia also extended to financial issues. On March 31, Flynn filed revised financial disclosure forms that included payments from three Russian companies with ties to the Kremlin prior to joining Trump's campaign.
Flynn was paid $45,000 as a guest speaker by RT, the Russian state-sponsored news outlet regarded by the U.S. government as a propaganda instrument. He was also paid $22,500 by two companies with close ties to the Kremlin for speeches. The speeches occurred in December 2015, shortly before he formally became a foreign policy adviser to Trump.