The rhetoric of intervention: On "taking sides in a civil war" | The Economist

"...the most to least compelling to the American public:

1) The most compelling: self-defense; responding to aggression against the U.S.

2) Using force to secure a resource or interest of the first magnitude for the U.S.

3) Defending a close ally who has been attacked

4) Protecting innocent civilians from a massive, deadly threat

5) Intervening in a foreign civil war on the side of friends

6) Bullying someone we don't like

It would be nice to see polling data to this effect, but this certainly sounds right. Mr Tesón comments:

Now in Libya 1), 2), and 3) are unavailable. That leaves 4), 5), and 6), and the Obama administration (and the U.N. Security Council) chose 4) as the rationale for the operation, protecting civilians, even though what the United States is really doing is 5), intervening in a civil war on the side of the rebels.

But imagine how public opinion would react should the President announce the truth: that it is helping the people of Libya depose a tyrant.

This is (U.N-authorized) humanitarian intervention, which seems more palatable than the more offensive-sounding "taking sides in a civil war." "

Full text: The rhetoric of intervention: On "taking sides in a civil war" | The Economist