When Lt. Col. Alexander Vindman appeared before members of Congress on Tuesday to discuss what he knew about President Trump’s conversations with Ukraine’s president, he was violating an order from his commander in chief not to cooperate with the House’s impeachment inquiry.

He is likely protected from legal ramifications from showing up to testify, a former Army judge advocate told Military Times on Thursday. But it remains to be seen whether what he told legislators could get him charged with a crime ― and, of course, how his choice to rebel against his White House chain-of-command will affect his career.

“It’s not far-fetched,” Sean Timmons, a managing partner at Tully Rinckey, said. “It’s a murky issue.”

It comes down to whether Trump’s order was lawful, he said. If Trump was trying to prevent Vindman from sharing sensitive information, it could be. If he was trying to prevent testimony, period, it’s not.

The Military Whistleblower Protection Act prohibits government officials from interfering with a member of the military in communicating with Congress or an inspector general. Adding to the complexity is that the president gets to determine what is and isn’t classified.

“If the president were to order the lieutenant colonel not to testify, that would not be a lawful order,” Timmons said. “However, it gets tricky, because you have to obey orders unless it is manifestly unlawful. It’s not clear if such an order would be manifestly unlawful if the president is using his executive authority to prohibit the communication of information that the executive branch determines to be classified, sensitive, top secret, not to be disclosed to anyone without prior authorization.”

In any case, Vindman’s testimony would need to be limited to avoid disclosing anything out of order, Timmons said.

The White House’s impeachment inquiry policy is laid out in an Oct. 8 letter from its senior counsel, Pat Cipollone, calling the investigation invalid and unconstitutional.

× Fear of missing out? Sign up for the Early Bird Brief - a daily roundup of military and defense news stories from around the globe. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

The Army, for its part, is publicly backing Vindman.

“Lt. Col. Vindman, who has served this country honorably for 20-plus years, is fully supported by the Army like every soldier, having earned a Purple Heart after being wounded in Iraq in 2004,” Army spokesman Matt Leonard told Military Times on Thursday. “As his career assignments reflect, Lt. Col. Vindman has a long history of selfless service to his country, including combat. Lt. Col. Vindman is afforded all protections anyone would be provided in his circumstances.”

A spokesman for the National Security Council, Vindman’s official command, declined to comment on whether he might face an Article 15 investigation.

“So I think, ultimately, it would be a gray area for the officer in question,” Timmons said. “What do I do here? Do I follow the president’s directive and comply? Or do I follow my conscience?”

And on the other hand, he added, if he received a subpoena from Congress and failed to comply, he could face charges of conduct unbecoming an officer under the Uniform Code of Military Justice.

Beyond any possible legal fallout, Timmons added, it’s more likely that Vindman has torpedoed his career by testifying before Congress.

“...the reality is, whistleblowers often face retaliation through subterfuge,” he said.

Because it’s unlikely Vindman will remain a member of the NSC staff, his service record will have a big gash in it from being moved mid-assignment, Timmons said.

His rater, who signs off on his officer evaluation report, is also likely a senior civilian official, who could give him a less-than-stellar review that might affect his competitiveness for promotion to full colonel. And then, of course, if he’s not promoted, he’ll eventually be forced to retire.

“Whistleblowers often sacrifice their careers because they face retaliatory acts from those superiors they reported against,” he said.

There are, on paper, protections from whistleblower retaliation, but very little guarantee he would be able to wade through the process successfully.

“He’s likely destroying his career, but he’s doing the right thing ― so, private employers, take that into consideration,” Timmons said.