Chelsea Manning, the U.S. soldier currently serving a 35-year prison sentence for leaking government documents to WikiLeaks, wrote a column for The Guardian criticizing Obama's approach to ISIS. "Based on my experience as an all-source analyst in Iraq during the organization's relative infancy, ISIS cannot be defeated by bombs and bullets," she writes.

Manning wrote the article from Fort Leavenworth, Kansas, where she's in military custody. She explains:

Attacking ISIS directly, by air strikes or special operations forces, is a very tempting option available to policymakers, with immediate (but not always good) results. Unfortunately, when the west fights fire with fire, we feed into a cycle of outrage, recruitment, organizing and even more fighting that goes back decades. This is exactly what happened in Iraq during the height of a civil war in 2006 and 2007, and it can only be expected to occur again.

Manning recommends a policy of containment instead: "Let ISIS succeed in setting up a failed 'state'–in a contained area and over a long enough period of time to prove itself unpopular and unable to govern. This might begin to discredit the leadership and ideology of ISIS for good."

This is the first time she's spoken out since entering custody. She's in the process of appealing her sentence.