Defense Secretary Pete Hegseth announced Monday that he has censured Democratic Sen. Mark Kelly of Arizona, a decision tied to Kelly’s participation in a video that urged troops to resist unlawful orders.

Hegseth said the censure is a formal letter with limited practical effect by itself, but he described it as “a necessary process step” in proceedings that could result in a demotion from Kelly’s retired rank and a subsequent reduction in his retirement pay.

In a lengthy post on social media, Kelly said he “never expected” what he called an “attack” from Trump and Hegseth. Kelly recounted his 25 years of Navy service, including combat and space missions, and said he would fight the censure “with everything I’ve got — not for myself.” He added that the point was to send “a message back” that Hegseth and Donald Trump do not get to decide what Americans can say about their government.

Hegseth’s action follows a video released in November by six Democratic lawmakers, all of whom previously served in the military or intelligence community, in which they addressed service members directly. The message urged U.S. troops to uphold the Constitution and defy “illegal orders,” without citing specific circumstances.

The 90-second video was first posted from Sen. Elissa Slotkin’s X account. In it, Slotkin acknowledged that service members are “under enormous stress and pressure right now,” and the group included Kelly and representatives Jason Crow, Chris Deluzio, Maggie Goodlander and Chrissy Houlahan.

Trump, a Republican, reacted to the lawmakers’ comments in a social media post days later, accusing them of sedition “punishable by DEATH.” The AP reported the video did not mention specific events, but was released amid a period of military actions, including attacks on boats accused of drug smuggling in the Caribbean Sea and the eastern Pacific Ocean, and amid Trump’s efforts to deploy National Guard troops to American cities.

The Pentagon said it began an investigation of Kelly in late November, citing a federal law that allows retired service members to be recalled to active duty on defense secretary orders for possible court-martial or other measures. Hegseth previously said Kelly was the only one facing investigation because he had formally retired from the military and therefore remained under the Pentagon’s jurisdiction.

Kelly disputed that rationale, saying last month that the investigation was an effort to silence dissent. In the AP report, Kelly said the message was essentially “do not speak out against this president or there will be consequences,” and he described the inquiry as pressure aimed at retired service members, active duty service members and government employees.

In his Monday post, Hegseth said Kelly’s remarks in the video and afterward violated Uniform Code of Military Justice provisions that prohibit conduct unbecoming an officer and violations of “good order and discipline.” Hegseth also warned that Kelly’s status as a sitting U.S. senator “does not exempt him from accountability, and further violations could result in further action.”

A retired Navy captain and judge advocate general, Todd Huntley, said the situation raises legal questions and called it a “novel” scenario. Huntley said one issue is whether Kelly’s comments are protected under the Constitution’s speech or debate clause, which he said is intended to prevent legislative intimidation by and accountability to the other branches of government.

Colby Vokey, a civilian military lawyer and former military prosecutor, said the clause should apply, arguing: “You can’t punish him for making statements that are consistent with the office he is holding.” Huntley said retirement grade determinations are fairly routine, but he noted that they are usually based on conduct during an individual’s active duty service—even if the conduct comes to light only after retirement. He added that he did not know whether conduct that occurs totally after retirement would meet the requirements for that kind of determination.

Vokey said he was skeptical about what “good cause” could justify any reduction in rank and pay grade for Kelly, saying: “I have no idea what the good cause would be. I think that’s pretty questionable.”

Hegseth said Kelly has 30 days to submit a response to the proceedings, and that a decision would be made within 45 days. Huntley said Kelly also has options to appeal within the military and in federal court, and Vokey said a federal court lawsuit would likely be the more effective course.