WASHINGTON — Sen. Mark Kelly sued Defense Secretary Pete Hegseth ​on Monday, saying Pentagon proceedings to demote the Arizona Democrat from his retired Navy captain rank violated Kelly’s free speech rights ⁠because he urged troops to reject unlawful orders.

Kelly, a retired Navy captain and former astronaut, ‌said in his lawsuit in federal court in Washington that the Defense ⁠Department’s actions were retaliatory and violated the Constitution’s First Amendment ‌protection of free speech.

The ‍lawsuit asked the court to block Hegseth’s review and declare ⁠his actions unlawful.

A Pentagon representative did not ⁠immediately respond to a request for comment.

In November, Hegseth blasted Kelly for appearing in a video that reminded service members of their duty to reject unlawful orders. In the clip, Kelly stated: “Our laws are clear: You can refuse illegal orders.”

Kelly’s remarks came as more Democrats were criticizing President Donald Trump’s decisions ‍to deploy the National Guard in U.S. cities and authorize lethal strikes on boats suspected of smuggling drugs from Latin America.

Hegseth issued a censure letter on January 5 accusing Kelly of “conduct unbecoming an officer.” The letter cited Kelly’s public criticism of military leadership and the November video.

In a statement on Monday, Kelly said Hegseth’s “unconstitutional crusade against me sends ‌a chilling message to every retired member of the military: if you speak out and say ‌something that the President or Secretary of Defense doesn’t like, you will be censured, threatened with demotion, or even prosecuted.”

Hegseth’s censure of Kelly followed a sweeping shakeup at the Pentagon during Trump’s second term. Several top military leaders ⁠were removed, including the chairman ​of the Joint Chiefs of Staff, ⁠the Navy’s top officer, ‌and the director of the National Security Agency.