Mr. Holder’s one-word answer — “no” — is not a step toward the greater transparency that President Obama pledged when he came into office, but has not delivered, in the realm of national security.

By declining to specify what it means to be “engaged in combat,” the letter does not foreclose the possible scenario — however hypothetical — of a military drone strike, against a United States citizen, on American soil. It also raises anew questions about the standards the administration has used in deciding to use drone strikes to kill Americans suspected of terrorist involvement overseas — notably Anwar al-Awlaki, the American-born cleric who was killed in a drone strike in Yemen in 2011.

Is there any reason to believe that military drones will soon be hovering over Manhattan, aiming to kill Americans believed to be involved in terrorist financing? No.

But is it well past time for the United States government to specify, precisely, its views on whom it thinks it can kill in the struggle against Al Qaeda and other terrorist forces? The answer is yes.