Al Qaeda hailed the failed Christmas Day airliner bombing over Detroit as a victory. They need all the victories they can get, as well as a new place to hide. Two years ago, there was an exodus of experienced al Qaeda personnel from Iraq to Pakistan and Afghanistan. But there they found the local Taliban openly hostile towards these foreign terrorists. There had been some recent battles between the Taliban and al Qaeda, in which hundreds of al Qaeda members had been killed. This was an old a problem with the al Qaeda foreigners, particularly the Arabs, who tended to look down on the Afghans as a bunch of ignorant hillbillies. Even in the 1990s, this was an issue, and it's gotten worse over time. Now the Americans have brought in their counter-terror commandos (which killed thousands of al Qaeda members in Iraq), and the Pakistani armed forces are invading tribal sanctuaries that had been al Qaeda bases for decades.
So, in the past year, al Qaeda people have been leaving Afghanistan and Pakistan and heading for Yemen and Somalia. In both cases, they have found themselves in even more hostile situations. In Somalia, there's a civil war among the local Islamic radicals, over whether they should support the al Qaeda goal of turning the world into one huge religious dictatorship, or simply concentrate on conquering Somalia for the cause of Islamic intolerance.
Yemen was supposed to be different, as the local government was willing to look the other way, as long as al Qaeda did no violence inside Yemen. That fell apart recently when the government learned that some al Qaeda factions were going to attack inside Yemen anyway. This was made worse when Saudi Arabia traced the attempted assassination of a senior Saudi prince back to al Qaeda in Yemen, and caught more al Qaeda members trying to get across the border with two suicide vests.
Al Qaeda in Yemen, which now includes the Saudi Arabian al Qaeda members who managed to survive the crackdown back home, thought the Yemeni government would be too busy fighting Shia rebels up north, to deal with terrorist hangouts. But Yemen got help from American commandos, cruise missiles and Hellfire equipped UAVs. So Yemen is no longer very safe for al Qaeda.
There are no good sanctuaries left.