"It seemed as though the benefits of acting militarily -- if we could obtain U.N. Security Council support -- exceeded the costs, in light of ... what we were seeing unfolding on the ground," Power told David Axelrod on "The Axe Files," a podcast produced by CNN and the University of Chicago Institute of Politics.
"I think we also had a sense -- and this is something you never really hear talked about today -- that Humpty Dumpty was already broken. There had already been a revolution and a revolution where people had expressed their revolt and revulsion at Gadhafi's form of rule over so many decades," she said. "The idea that this was going to be put tidily back into the box if one just stood back, I think, was extremely unlikely ... It's not as if (Gadhafi) goes into Benghazi and hunts people down like rats and that's the end of this revolution. So some amount of instability is going to exist in this area now that it's been unleashed."
Gadhafi was killed in October 2011, but President Barack Obama has said the worst mistake of his presidency was a lack of planning for the post-Gadhafi period, as the country now faces a new threat: defeating ISIS.
Power acknowledged that one misstep the U.S. made was underestimating Libya's opposition to a foreign troop presence once Gadhafi was toppled.
"The aftermath has proven very challenging and ... one of the things we didn't anticipate was just how anti-foreigner a country that had just had an intervention occur carried out by foreigners -- how anti-foreigner that they would be," Power said, noting that the Libyans "wanted international support on the front end" but not beyond.
Despite the challenges that Libya now faces, Power remains a staunch defender of the Obama administration's intervention there.
"We have a chance now -- in supporting the U.N. effort -- to broker some sort of political coalition that governs the country," she said. "There's more hope now than there's been over the last year and a half. But the cleavages in the society are extremely deep."
She added: "I don't think that one can say today that had the President not made the decision he did ... that you'd have the Libya that existed before the protests started, which is somehow how the conversation plays out. I think (that's) is very naïve."
During the conversation with Axelrod, Power also explained the administration's decision not to take military action in Syria, despite repeated calls by critics for a no-fly zone.
"There are a lot of tools in play, but when you look at the different military options, it's very hard to see a scenario where that's what resolves the situation in Syria. A military solution -- it's hard to see that," she said.
She also defended the continued efforts by the U.S. to work with Russia even in the midst of repeated disputes with Russian president Vladimir Putin.
"It would be reckless to walk away from a country that has that much influence and just say as a form of moral protest or indignation, you know, we're going to take our marbles and go home," she said.
To hear the whole conversation with Power, which also touched on her childhood in Ireland, her Pulitzer Prize-winning book on U.S. foreign policy, what the future holds for Europe and China and her post-U.N. plans, click on http://podcast.cnn.com
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