The US is a nation, and a nation has its armed forces. The purpose of those armed forces is to serve, in a potentially violent capacity, the greater benefit of that nation. Whether that armed forces actions are ethical or not is mostly irrelevant. They do not exist for ethical purposes. They exist to fight and kill, either in offense or defense. many would say that alone is inherently unethical. If what they do benefits the country then they are doing their job. Morality doesn't play a role.
I hate to use the terrible phrase "support the troops," because really, what do we do that supports them? But am I generally in favor of the troops? On an individual level perhaps. As I said, they do their job. Ethics don't mean a thing. However, I am not so in favor of the people giving the troops their orders.