In the Wall Street Journal today I make the case for continuing the counterinsurgency campaign in Afghanistan despite the death of Osama bin Laden. Al Qaeda remains a threat, I argue, and more importantly so do numerous associated groups, ranging from the Quetta Shura Taliban and the Haqqani Network to the Pakistan Taliban and Lashkar-e-Taiba, which operate out of Pakistan. Having a robust military presence in Afghanistan is our best bet to counter these groups and prevent the emergence of a fundamentalist caliphate stretching from Kashmir to Kabul and beyond.

But in many ways figuring out what to do in Afghanistan is easier than figuring out how to handle Pakistan. The death of bin Laden—in a house located in a military garrison town just 35 miles north of Islamabad—reveals once and for all the bankruptcy of our existing policy toward Pakistan. Since 9/11 we have been cajoling and browbeating the Pakistanis into cracking down on jihadist groups. We have provided military hardware, trainers, and billions of dollars in aid to sweeten the pot. None of it has led to a fundamental realignment of Pakistan’s policy.

The Inter-Services Intelligence Agency continues to support terrorist groups such as the Taliban and the Haqqani network while turning a blind eye—at the very least—to the presence of senior Al Qaeda leaders in the heart of their country. It also is not above poking a finger in our eye when piqued, whether by detaining a CIA employee or by leaking the name of the CIA station chief.

To be fair, Pakistan has also cooperated with American drone strikes and sent its own troops to battle militants in areas such as South Waziristan. But the Pakistani army brass, which call the shots in Pakistani politics, seem fundamentally ambivalent about extremist groups. They may worry that these organizations will try to take over Pakistan itself, something that whisky-drinking generals oppose, but at the same time they see these groups as potent agents of Pakistani power projection in neighboring states.

There is a compelling case to be made for presenting Pakistan with an ultimatum. Either it assists us in snaring the remaining Al Qaeda leaders, especially Ayman al Zawahiri, or its aid is cut off. The question is what happens if Pakistan calls our bluff. Are we prepared to follow through? Because cutting off Pakistan could have all sorts of dangerous consequences.

In the first place it could lead Pakistan to retaliate by stopping all cooperation with drone strikes and with the U.S. mission in Afghanistan, which is supplied in part through the Pakistani port of Karachi. The shipments that go through Karachi could probably be replaced by an airlift or by supplies shipped through Central Asia, but this would be expensive and time-consuming.

Secondly, cutting off, or even seriously decreasing, our aid to Pakistan could further imperil the stability of an already shaky regime. We may not much like dealing with Gen. Ashfaq Parvez Kayani, the army chief of staff, but better him than some bearded mullah.

So what should we do? Frankly, I am not sure. All I know for sure is that our present policy isn’t working.