Who is Mark Kelly, and why is the US senator accused of ‘sedition’?

The United States Department of Defense has launched an investigation into Senator Mark Kelly over a video in which he and other Democrats urged soldiers to defy “illegal orders”.

The video was released last week. It features six Democratic lawmakers who previously held positions in the military and intelligence services: Kelly, Representatives Chris Deluzio and Chrissy Houlahan of Pennsylvania, Representative Maggie Goodlander of New Hampshire, Representative Jason Crow of Colorado and Senator Elissa Slotkin of Michigan.
Slotkin wrote on X in a post accompanying the video that they wanted to “speak directly to members of the military and the intelligence community”.

“The American people need you to stand up for our laws and our Constitution. Don’t give up the ship,” Slotkin wrote.
In the video, the lawmakers said the trust that citizens have in the US military and intelligence agencies was “at risk”.

“This administration is pitting our uniformed military and intelligence community professionals against American citizens,” the lawmakers said.

“Like us, you all swore an oath to protect and defend this constitution. Right now, the threats to our constitution aren’t just coming from abroad but right here at home,” the video added.
“Our laws are clear: You can refuse illegal orders.”

In response to the video, the Pentagon has announced an investigation into alleged breaches of military law by Kelly, a former navy captain, which is an unusual step against retired military personnel.

According to the US Manual for Courts-Martial, which outlines conduct in the military: “An order requiring the performance of a military duty or act may be inferred to be lawful and it is disobeyed at the peril of the subordinate.”

However, that inference does not apply if an order is contrary to the constitution or US law, is given by an officer without the authority to issue it or is “patently illegal”, such as ordering the commission of a crime.