Robert Chesney offers another reason why the Obama administration is pushing an increased role for the CIA in Yemen--if President Ali Abdullah Saleh goes, with him goes the consent necessary to operate drone strikes conducted by the military, but thinks this is unnecessary from a legal perspective:
The thing that jumps out as potentially relevant here is that, absent host nation consent, a use of force on that state's territory presumptively violates its sovereignty under UN Charter Article 2(4). So perhaps the idea is that this is ok for the CIA to do via a covert action, but not ok for DOD to do. But is this really a dispositive concern here? Article 2(4) is not ironclad. An objection from Yemen under Article 2(4) would fail in the face of a U.S. Article 51 self-defense claim insofar as Yemen is unable or unwilling to use its authority to address the threat posed by AQAP itself. So long as one accepts that such unable/unwilling arguments can be made, the Yemen scenario seems like a very plausible place to invoke it. If that's right, then DOD would not face an Article 2(4) hurdle in acting without Yemen's consent.
Ken Gude argues that lack of permission, and the absence of the kind of human intelligence network present in Afghanistan and Pakistan, is exactly why the U.S. shouldn't continue drones strikes if it lacks permission to do so:
The absence of cooperation is precisely the problem with choosing this moment to increase airstrikes on AQAP. Yemen is a chaotic, confusing place in the best of times. Now, with a popular protest movement, top military commanders defecting, a violent split in the major tribal federation, and Islamists other than AQAP all competing with a very weak central government with a wounded president and other top leaders out of the country, getting good information on who to target with these airstrikes is practically impossible. There is real potential for U.S. airstrikes to either be misdirected or explicitly manipulated by local groups to target rivals.
I'm pretty sympathetic to Gude's concerns.