Marc Lynch has a smart post on Yemen that all and sundry should read.
Obviously, I’m no kind of Yemen expert. But in the broadest possible sense the challenge posed by these kind of problems is that you need to find a middle ground in terms of commitment. The risk, as Lynch says, is that if you make hasty decisions in response to political pressure you wind up overcommitting in a way that leads to investing too little attention and resources to other places. You need to be able to say that the United States has interests in Yemen, and interests in Afghanistan, and interests in Pakistan, and interests in other countries without any of these things necessarily being an “existential threat” or a “war of necessity.”