I won't share opinion on this because of what I do.
That being said...Americans have been tortured, maimed, and brutally executed by ISIS and other organizations out there who have no regard whatsoever for the Geneva Convention. The thing about international laws like that is, it's more of a mutual agreement between countries who are saying "yep we won't use Agent Orange" or "yep we won't torture people". There are plenty of countries who don't give a damn. Some will say they comply, then do underhanded stuff. Others will outright violate the conventions.
Something we have to understand is that fighting insurgents is not like fighting a conventional enemy. There is a reason why the push into Iraq took a matter of days, while the fighting in Iraq, Afghanistan, and abroad has been raging on for years. It is because they are cowards, they know they cannot win against us head on, so they hide behind women and children and use our own rules of engagement against us.
Same goes for treatment of prisoners. They know that we won't mistreat POWs. They don't hold themselves to our standards.