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Yemen has suddenly joined Afghanistan and Pakistan as a risk to global security. Indeed, it is increasingly seen as a nascent failed state and potential replacement host for Al-Qaeda.

The attempted bombing of a Detroit-bound airliner on Christmas Day by a young Nigerian man trained by Al-Qaeda in Yemen appeared to open the West’s eyes to the country’s problems. Following that failed attack, US President Barack Obama and British Prime Minister Gordon Brown jointly pushed a conference in London to propose solutions for the previously overlooked crises in Yemen.

But if the conference focuses too narrowly on...