A journalist today asked President Trump if LTC Alexander Vindman should face disciplinary action for testifying before Congress. President Trump of course indicated that might be a possibility. This would be a two fold problem for the President, neither of which I am sure the President would want to deal with.
First off, Federal law protects whistle blowers from retaliation. If LTC Vindman's lawyer can show that he testified in good faith, court martialing him would be against the law and would likely never go to trial. This would be the likely outcome as there is ample evidence corroborating LTC Vindman's testimony.
Second, even if through pressure from the White House he was court maritaled, this would open up a whole new can of worms for the President. In this case, it would be up to the prosecution to prove that LTC Vindman lied under oath. During the impeachment hearings, the White House defense team did not produce a single shred of evidence to the contrary. In fact several Republican Senator's said they believed the President committed the crime he was accused of, that the House Managers had proven their case, but they did not believe this rose to the level of an impeachable offense.
So the problem facing the prosecution would be how to prove LTC Vindman lied under oath if no one who could say otherwise would be willing to testify under oath themselves. Nor would the White House be willing to release any documents that could prove the case one way or the other. It would also be very likely that the defense would call sitting members of the House of Representatives to testify on his behalf. This would be a very ugly situation for the AG and any Army lawyer designated to prosecute the case.
On top of that, it would be a near guarantee that LTC Vindman would have
a very high profile and expensive lawyer defending him. The first thing this team would do is subpoena the real transcript and every person who was on the call. The President could of course fight this, but he would not be fighting it in a civilian court where it might take years to make it way to the supreme court. In the military court system there is the "Intermediate service courts of criminal appeals" and the "Court of Appeals for the Armed Forces", both of which can be convened very quickly and would not take months to make a decision. The case could be appealed to appellate courts, but the civilian judiciary has very rarely accepted cases coming out of the Military and it is very unlikely they would be willing to take this case on themselves. However I suspect the case would be thrown out before it got to this point for lack of evidence that LTC Vindman did anything but testify in good faith and fighting it would in and of it self be evidence that the White House did not want to incriminate itself.
The best thing the White House can do is let this die down and let LTC Vindman quietly retire in a couple of years.
Edit: I would also point out that in all likely hood LTC Vindman considered the order from the President to defy subpoenas issued by Congress was an illegal order. Considering that the order was issued to cover up a probable crime by the president, he was correct in disobeying the order, in fact it was his duty to disobey that order. For those of you who do not understand this, here is a pretty good article discussing the topic.