Republican Representative Thomas Massie of Kentucky moved on Tuesday to impeach Secretary of Defense Pete Hegseth over the ongoing war in Iran.

Massie, a long-time critic of the Trump administration, read the articles of impeachment aloud from the House floor shortly after the chamber convened at noon.

The congressman alleges that Hegseth waged the Iran war illegally, defied Congress' order to withdraw from the conflict, and incurred unnecessary civilian casualties, among other "high crimes and misdemeanors."

Massie has repeatedly clashed with members of his own party in recent years. He is leaving office after losing his primary to an opponent backed by President Trump. Beyond the Iran war, Massie worked alongside Democratic Representative Ro Khanna of California to compel the Trump administration to release files related to convicted sex offender Jeffrey Epstein.

Republicans in theory hold enough votes to defeat the impeachment proposal, though it could prove a complicated vote for members representing competitive electoral districts.

The war has been deeply unpopular among the American public and has contributed to rising costs in the United States. The administration maintains the conflict was necessary to prevent Iran from obtaining a nuclear weapon, though experts say the country was not close to developing one before the conflict began six months ago.

The Pentagon defended Hegseth following the move. "Secretary Hegseth has been a transformative leader for the Department of War," Pentagon press secretary Kingsley Wilson said in a statement. "The entire Department is unified behind the Secretary's vision and will continue working to put our warfighters and America first."

The House must act on Massie's proposal by Thursday. The chamber is set to leave Washington this week for an extended recess that will not end until after the midterm elections in November.