If Pakistan really does fall apart, the United States will have to turn to Plan B. One scenario is that the U.S. could abandon Islamabad in favor of separatists in Baluchistan, a large province that borders Iran and Afghanistan and that has a large Chinese-built port at Gwadar—thus offering a route into southern Afghanistan. Of course, any talk of an American plot to dismember Afghanistan doesn’t really warm the cockles of Pakistani hearts.

The danger for President Obama is that his presidency is, after a few short months, entering its LBJ phase. Faced with a mounting economic crisis at home, there is a real possibility that the Talibanization of Pakistan will force him to deploy U.S. forces amidst a population that, to put it mildly, wouldn’t greet their arrival with flowers and chocolates. Obama’s commitment to his domestic reform agenda would be sorely tested by a shooting war in Pakistan, not least because the anti-war left would—very understandably—be in open revolt.