When the military authorities lie about an incident like this, and try to cover up the facts, that's not revenge, and it's not done in the heat of the moment.   

In normal life that kind of thing is called "being an accessory after the event", and "conspiracy to obstruct justice", and is a criminal activity.

It could be possible that the soldiers who did the killing may not in fact have been guilty of murder. There is no question at all that the military authorities subsequently and repeatedly lied about what happened.

But whatever happens to the people who pulled the triggers,if anything, you can guarantee that no one is going to be prosecuted for ordering or taking part in the cover-up. After all the people who tried to cover-up My Lai were never punished. One of them, a Major Colin Powell, was quite successful in his later career...