There's no requirement that they be "unlawful" nor that they be on a "battlefield" -- nowhere in the Constitution are such provisos appended to the Commander in Chief power. The British soldiers who fought the Americans in the Revolutionary War were not unlawful combatants, but that didn't stop your heroes from attacking, killing and capturing and holding them prisoner when they could ... even when they weren't on a "battlefield." Again, identification and engagement of the enemy are military functions under the purview of the Commander in Chief. Your opinion that "[t]hey're just people we don't like" is just your own and irrelevant. You're not in a position to make that call, and it's neither your right nor responsibility; nor is it that of our fine countrymen in black robes. Again, that function is assigned by our Constitution to the President, which Judge Kaplan, in his wisdom, upheld.