The legal parameters defining the use of military force against terrorists are unquestionably difficult to draw. On the one hand, no one disputes that it is permissible to kill an enemy soldier on the battlefield in an ongoing armed conflict. On the other hand, absent extreme circumstances, constitutional and international law bar a state from killing a human being in peacetime without a trial (and even then, many authorities hold that capital punishment violates international human rights law). Al-Qaeda has not limited its fight to the battlefield in Afghanistan, and most agree that, as long as sovereignty concerns are met, the use of military force can follow this enemy beyond the battlefield at least in some situations. Killing Osama bin Laden in Pakistan—whose tribal areas are for all practical purposes part of the theater of war—was the justified targeting of the enemy’s leader. But are al-Qaeda in the Arabian Peninsula or al-Shabab the same “enemy,” or merely sympathetic adherents of a terrorist philosophy? They certainly did not attack us on September 11, nor are they harboring those who did. Can we summarily execute all terrorists who we fear might someday commit a terrorist act against us? Brennan’s speech offered no answers.
And that makes it especially disturbing that the contours of US policy and practice in this area remain largely secret. Presumably the administration has developed criteria for who can be killed and why, and a process for assessing who fits those criteria and when their targeting is justified. But if so, it hasn’t told us. Instead, it exercises the authority to kill, not only in Afghanistan and the border regions of Pakistan, but in Yemen,Somalia, and presumably elsewhere, based on a secret policy. We learn more about its outlines from leaks to The New York Times than from the cryptic comments of US officials in speeches like Brennan’s. If we are engaging the enemy within the rule of law, as Brennan insisted we must, we should have the courage to make our policies transparent, so that the people, both in the United States and beyond, can judge for themselves. And if, by contrast, we continue to justify such practices in only the vaguest of terms, we should expect other countries to take them up—and almost certainly in ways we will not find to our liking.