No. 1 Pakistan
The U.S.'s war in Afghanistan, launched weeks after the 9/11 terrorist attacks, has come full circle. While the Taliban regime had been deposed and al-Qaeda forced on the run, the prosecution of the war has not brought about stability to the region.
In fact, it has escalated over the past few months, and it's poised to spill over on a grand scale to neighboring Pakistan, whose standing as an U.S. ally has frequently come into question, particularly after the ouster of former strongman president Pervez Musharraf.
President-elect Obama broached the possibility of launching attacks inside Pakistan's borders without that country's authorization in a 2007 speech - something that's since been carried out routinely in the form of missile strikes and commando incursions by the Bush Administration. So far, Pakistan's fragile government has done little other than lodging toothless protests.
President Asif Ali Zardari indeed has much larger problems on his hands than occasional violation of his country's sovereignty by the Americans. Pakistan is broke and just reached an agreement with the IMF for a $7.6 billion emergency loan. Its porous northwest borders are out of reach for its overstretched military and a hotbed for al-Qaeda and a reconstituted Taliban. And a large part of its Muslim population resents the U.S. presence in the region and the growing clout of archenemy India.
In September, the Marriott Hotel in the heart of capital Islamabad was bombed by home-grown terrorists, raising more concerns about the nation's stability. Should Zardari's government collapse and be swallowed up by an Islamist uprising, the entire sub-continent may be consumed by instant conflagration. With both Pakistan and India in possession of nuclear weapons, this will be a 3 a.m. call that President-elect Obama dearly wishes to avoid.