US military support (air cover) for libyan anti-government forces, without any Congressional authorization. This would qualify as an act of war if Mexico did this to the US.
Whether we call something a civil war/insurrection or a revolution depends largely on which side you put your allegiance. The same is true for foreign support of the group trying to overthrow the government.
I think we had a favorable view, for example, of the help France gave our founding fathers in the American Revolution.
However, I too criticized Obama for not getting Congressional authorization for the war powers he exercised in the Libya "no fly zone". I reject utterly his argument that it doesn't count as military intervention if there are no boots on the ground.
I also argued that the U.N.Charter prohibits intervention in a sovereign country's internal strife if there isn't a credible threat to regional peace. (Though that criticism goes against the entire UN rather than against Obama--particularly against the self-contradictory UN resolution used to establish the so-called "no fly zone". It called for an immediate cease fire, but in practice, it only called for a cease fire from the Gaddafi government, and not also from the rebels who were being supported by the "no fly zone".)
Note well: I'm certainly not saying I would have preferred that the government put down the rebellion. I'm merely pointing out that it really wasn't our decision to make--at least not under our own laws.
I also criticized Obama for throwing support behind the rebels without knowing that we weren't possibly supporting terrorists, and when we knew for sure they weren't working toward establishing a secular democracy (and I don't believe there can be such a thing as a Muslim state that is a democracy--in other words, that such a thing as a theocratic democracy is possible).
However, none of this is justification for the incoherent criticisms I've been hearing against Obama for the attack on our embassy in Benghazi.