Most of the terrorists and insurgents that the U.S. military and the CIA targets in the war against al-Qaida have nothing to do with the 9/11 attacks. But the act of Congress, passed days after the attacks, authorizing that war tethers U.S. action to 9/11. You might argue it’s time for an upgrade. The Obama Pentagon doesn’t want one.

The language of the 2001 Authorization to Use Military Force is “solid” and “sufficient to address the existing threats that I’ve seen,” Jeh Johnson, the Pentagon’s top lawyer, told the House Armed Services Committee on Thursday afternoon.

That may seem like the Obama administration is in the rare position of rejecting an expansion of its warfighting powers. But although no one at the hearing is willing to say it, politics submerged barely beneath the rhetorical surface are driving Johnson’s antipathy to a renewed authorization. Here’s why.