If you haven't already, I recommend watching -- or reading -- the president's address on the intervention in Libya. It's not especially persuasive, but for those baffled by the president's current actions -- and wondering what happened to the Barack Obama of 2008 -- it provides an opportunity for inquiry:
It is true that America cannot use our military wherever repression occurs. And given the costs and risks of intervention, we must always measure our interests against the need for action. But that cannot be an argument for never acting on behalf of what's right. In this particular country - Libya; at this particular moment, we were faced with the prospect of violence on a horrific scale. We had a unique ability to stop that violence: an international mandate for action, a broad coalition prepared to join us, the support of Arab countries, and a plea for help from the Libyan people themselves. […]
To brush aside America's responsibility as a leader and - more profoundly - our responsibilities to our fellow human beings under such circumstances would have been a betrayal of who we are.
Compare this to candidate Barack Obama's answer to Tom Brokaw in the second presidential debate:
BROKAW: Senator Obama, let me ask you if -- let's see if we can establish tonight the Obama doctrine and the McCain doctrine for the use of United States combat forces in situations where there's a humanitarian crisis, but it does not affect our national security.
Take the Congo, where 4.5 million people have died since 1998, or take Rwanda in the earlier dreadful days, or Somalia. What is the Obama doctrine for use of force that the United States would send when we don't have national security issues at stake?
OBAMA: Well, we may not always have national security issues at stake, but we have moral issues at stake. […] And so I do believe that we have to consider it as part of our interests, our national interests, in intervening where possible.
But understand that there's a lot of cruelty around the world. We're not going to be able to be everywhere all the time. That's why it's so important for us to be able to work in concert with our allies.
Let's take the example of Darfur just for a moment. Right now there's a peacekeeping force that has been set up and we have African Union troops in Darfur to stop a genocide that has killed hundreds of thousands of people.
We could be providing logistical support, setting up a no-fly zone at relatively little cost to us, but we can only do it if we can help mobilize the international community and lead. And that's what I intend to do when I'm president. [Emphasis mine]
With a few obvious differences -- the United States has deliberately shied away from an explicit leadership role -- this is the exact strategy Obama has followed for the intervention in Libya. Liberal consternation notwithstanding, Barack Obama's foreign-policy views aren't meaningfully different from his views in 2002, when he spoke against the Iraq War; 2006, when he published The Audacity of Hope; 2008, when he won the presidency; and 2009, when he won the Nobel Peace Prize. Put another way, Obama is a mainstream Democrat, and like most mainstream Democrats, he supports humanitarian interventions and an engaged use of American military power (in concert with allies and the international community).
Given President Obama's past statements, the president's relative free hand in foreign policy, and the structural/political bias toward military intervention, I'm not terribly surprised by the Libyan intervention. Sooner or later, something like this was bound to happen.