A student asked me last in week in class why the US is involved in Libya which is a NATO operation? He was trying to make a point that both NATO and UN have a large collective military capability when you take into consideration all members collectively. In theory, this makes sense but in practice reality does not match theory.
Case in point, NATO is asking the US for more airstrikes because only the US has the aircraft that can accurately strike in all weather conditions. Specifically, NATO needs US A-10 and AC-130 aircraft to remain on-station. NATO lacks these types of close air support that can strike Libyan forces that are in close proximity to civilians.
Apparently NATO is skittish after one of their airstrikes last week left 40 civilians dead.
The US is turning into Michael Corleone in The Godfather III when he says, "Just when I thought I was out, they pull me back in!"