[Lance Corporal Greg Buckley] wasn't killed in a firefight on a battlefield, or by a roadside bomb while on patrol. The 21-year-old was working out with fellow Marines at the base gym when an Afghan teenager walked in carrying an AK-47 -- and emptied the clip, killing Buckley and two others.
But Buckley was, in fact, killed in a firefight on a battlefield.
When the armed forces of one country invade and occupy another country, both countries, in their entirety, become battlefields and remain so until the war ends (really ends, not just formally ends).
Buckley's death is referred to as a murder, and that's true -- to the extent, and only to the extent, that all battlefield deaths are murders.
The US Marine Corps was obviously guilty of poor operational security in letting a local warlord bring male sex slaves onto its base and letting those sex slaves wander around unaccompanied by armed escorts at all times. But that's really the extent of it.
The thing about war is that it -- by "it" I mean the forces conducting it -- don't respect ideas like "we're having a wedding here, don't call in an airstrike" or "but this base is in the US ... an attack here is terrorism!" or "just because my dad said things you didn't like and you killed him with a drone strike doesn't mean you should also kill me in the same way because I 'chose the wrong father.'"
Americans seem to want to have it both ways ... especially American politicans, who haven't bothered to legally declare war on anyone since the 1940s and who don't want it to be war when, for example, they warehouse a bunch of prisoners at Gitmo and pretend they aren't POWs and so forth, but really most Americans. But they can't have it both ways. Go to war, reap the whirlwind. Whining about that is unseemly. If you don't want the fruits of war, don't plant the seed.