It looks like Pakistan is acting up again. This is no surprise as Pakistan has been fighting Islamic nationalists for decades. I believe that Pakistan is losing and the moves to block supply of NATO forces in Afghanistan are just the latest moves.
Pakistan was behind the Taliban obtaining power in Afghanistan back in the late 1990’s. I believe that the Pakistani government began to work with the U.S., as President Musharraf was a good ally. Now that he is gone, I believe that Pakistan is beginning to swing back to its old ways. Not that it was fully in our camp, but the while the decision maker was Musharraf, the Pakistan military was helping the U.S. more than it was working against us. I believe this to be a different case today.
Remember how Turkey pulled its authorization for the U.S. to base our troops out of Turkey just 48 hours before our assault on Iraq? Even though Turkey is a different situation, Pakistan can easily turn out to be worse. It will not be known for certain for many years, but this can be a situation where our divisive President has made an uncertain ally into a definitive enemy.