Washington DC - A judge on Thursday temporarily blocked the Pentagon's efforts to punish Democratic Senator Mark Kelly over a video in which he and other lawmakers urged military and intelligence personnel to disobey illegal orders.

The preliminary injunction is the latest blow to President Donald Trump's efforts to target the lawmakers – whom he initially accused of "seditious behavior, punishable by death" – after a federal grand jury rejected the Justice Department's attempts to indict them earlier this week.

"Defendants have trampled on Senator Kelly's First Amendment freedoms and threatened the constitutional liberties of millions of military retirees," Judge Richard Leon wrote in his opinion, adding that Kelly's claim "is likely to succeed on the merits."

Kelly, a decorated Navy veteran and former astronaut, had asked the court to declare a censure letter placed in his file as well as efforts to potentially reduce his military rank in retirement – and thus his pension – to be "unlawful and unconstitutional."

The lawsuit – which names Pentagon chief Pete Hegseth, the Defense Department, Navy Secretary John Phelan, and the department he heads – said their actions "violate numerous constitutional guarantees and have no basis in statute."

Kelly hailed the ruling, saying in a statement that the court "made clear that Pete Hegseth violated the Constitution when he tried to punish me for something I said."

In the November video, the lawmakers said Trump's administration was "pitting our uniformed military and intelligence community professionals against American citizens."

"Right now, the threats to our constitution aren't just coming from abroad, but from right here at home," they said, adding: "You can refuse illegal orders."

The lawmakers in the video did not specify which orders they were referring to, but the Trump administration has come under fire over its controversial use of US forces both at home and abroad.