Sen. Mark Kelly officially sued the Pentagon and Secretary of Defense Pete Hegseth over allegations that he violated the Constitution while participating in a video to U.S. troops, CNBC reports.

The federal civil lawsuit was filed in U.S. District Court in Washington on Monday (January 12), one week after Hegseth announced his intention to cut military retirement pay for Kelly, a former United States Naval officer who ranked as captain and served in the Gulf War. Kelly's lawyers accused the government of attempting to “trample on protections the Constitution singles out as essential to legislative independence" in the lawsuit, which was also filed against the U.S. Navy Department and its secretary John Phelan.

“It appears that never in our nation’s history has the Executive Branch imposed military sanctions on a Member of Congress for engaging in disfavored political speech,” the lawyers wrote.

Fellow Democrat Sen. Ruben Gallego previously bashed Hegseth after the Pentagon announced its investigation into "serious allegations of misconduct" against Kelly and five other Democrats calling on service members to "refuse illegal orders."

“You will never, ever, ever even be half the man that Sen. Kelly is,” said Gallego, a former Marine, about Hegseth during an appearance on CNN’s The Arena with Kasie Hunt. “You, sir, are a coward! And the fact that you are following this order from the president shows how big of a coward you are. And I can’t wait till you no longer are the Secretary of Defense.”

President Donald Trump called on the arrest of Kelly and Democrat Sen. Elissa Slotkin of Michigan, Reps. Chris Deluzio and Chrissy Houlahan of Pennsylvania, Rep. Maggie Goodlander of New Hampshire and Rep. Jason Crow of Colorado over a video in which he claimed all showed SEDITIOUS BEHAVIOR AT THE HIGHEST LEVEL” which he said was "punishable by DEATH" in posts shared on his Truth Social account on November 20. Hegseth referred to the lawmakers as the "Seditious Six" while announcing the investigation of Kelly and referred to the video as “despicable, reckless and false … Kelly’s conduct brings discredit upon the armed forces and will be addressed appropriately,” via the New York Post.

Hegseth confirmed that Kelly was the only member of the group subject to War Department discipline as he is a retired Naval officer.