he broke the chain of command.
you don't get to captain an aircraft carrier and leak a letter like that to the press. He likely knew this would be the result when he did it. That may be courageous and honorable and the right thing to do. But there's no way he could remain in command after this.
We're going to need a lot more ethically courageous people like him to blow the fucking whistle on everything this corrupt and immoral administration is doing right now. Over and over until Trump is removed permanently.