Chairman Sen. Richard Burr, R-North Carolina, and Vice Chairman Sen. Mark Warner, D-Virginia, said in a statement that the subpoena requests documents relevant to the investigation. They also noted that they had asked Flynn for the documents in late April, but that "he declined, through counsel, to cooperate with the Committee’s request."
Flynn's lawyer declined ABC News' request for comment, but referred back to his statement released on March 30.
In the statement, Flynn's lawyer wrote that "General Flynn certainly has a story to tell, and he very much wants to tell it, should the circumstances permit.
"Out of respect for the Committees, we will not comment right now on the details of discussions between counsel for General Flynn and the House and Senate Intelligence Committees, other than to confirm that those discussions have taken place. But it is important to acknowledge the circumstances in which those discussions are occurring," the statement continued.
The statement blasted the media for propagating "unfounded allegations, outrageous claims of treason, and vicious innuendo directed against him" and members of Congress for making "unsubstantiated public demands ... that he be criminally investigated."
"No reasonable person, who has the benefit of advice from counsel, would submit to questioning in such a highly politicized, witch hunt environment without assurances against unfair prosecution," the statement read.