Lawrence Wright, author of "The Looming Tower," poses the right question in his most recent article for The New Yorker.

"What would happen," he asks, "if the Pakistani military actually captured or killed Al Qaeda’s top leaders?"

The answer is that American aid would dry up shortly thereafter, just as it did after the Soviets were driven out of Afghanistan by jihadis and warlords (fueled by US money, hardware and intel).

Pakistan's military leadership made that mistake (of not keeping a war going) once. They were determined never to make it again. So after 9/11, they immediately aligned with the United States to defeat Al Qaeda, knowing that as long as the war was "hot," the US aid money would continue to flow. A year became two years, Two years became a decade. Pakistan's military (and Pakistan's economy) became addicted to US aid.

Wright continues:

The main beneficiary of U.S. money, the Pakistani military, has never won a war, but, according to “Military Inc.,” by Ayesha Siddiqa, it has done very well in its investments: hotels, real estate, shopping malls. Such entrepreneurship, however corrupt, fills a gap, as Pakistan’s economy is now almost entirely dependent on American taxpayers. In a country of a hundred and eighty million people, fewer than two million citizens pay taxes, and Pakistan’s leaders are doing little to change the situation. In Karachi, the financial capital, the government recently inaugurated a program to appoint eunuchs as tax collectors. Eunuchs are considered relentless scolds in South Asia, and the threat of being hounded by one is somehow supposed to take the place of audits.

Now that Pakistan's military can no longer pretend that it is "fighting" Al Qaeda, what will it do? The short answer is "play the nuclear card." Pakistan is a nuclear state. Whenever it is pressed for leverage, it whispers into the ears of American diplomats and military leaders that it cannot be sure these weapons can be kept out of the hands of terrorists without significant US financial aid. Generally speaking, this "threat" has been rewarded. The United States has kept on paying.

The question now is whether that changes; whether the Pakistan scam is finally shut down. We'll see, In the meantime, Wright's article provides the best overview we've seen of how we got here, where things stand now and what the options are going forward.