For reasons I explain here. Highlight reel: it's disingenuous to claim, as John Brennan did this afternoon, that al-Qaida is a spent force that requires a global war to combat it. (Brennan said it's not a global war anymore. Just a war in, like, Pakistan, Yemen, Somalia, Iraq, the Sahel...)
It would be one thing if Brennan said that we're on the precipice of destroying al-Qaida, but we just need a little more effort to break its back. Brennan could have alternatively argued that al-Qaida just isn't that dangerous anymore, so we don't need this overwhelming expenditure of resources to get rid of it. If he didn't like any of those arguments, he could have said that al-Qaida remains virulent in a variety of places around the world, notwithstanding its inexorable collapse under the historic and ideological weight of the Arab Spring, so we go forth into the world destroy this monster.
But Brennan said all of those things. Worse, neither he nor the strategy that I presume he authored gives you any criteria to judge when al-Qaida is actually dead and buried. Instead, we can "for the first time... envision of the demise of al-Qaida's core leadership in the coming years." As it happens, I can envision a lot of things. How do I know when al-Qaida ceases to exist? A strategy for "Ensuring al-Qaida's Demise," the title of Brennan's speech, ought to, at the least, ensure al-Qaida's demise.
You might as well imagine that the rash of post-9/11 laws expanding the ambit of domestic surveillance might cease to exist after their rationale has passed from the scene. Nothing would be more naive. Brennan: "We must have a legal framework that provides our extraordinary intelligence, counterterrorism, and law enforcement professionals with all the lawful tools they need to do their job and keep our country safe. We must not tie their hands." In other words, a permanently expanded security state -- to combat a spent historic force.