WASHINGTON – The nation’s vexation over the morality and legality of President Obama’s drone war has produced a salutary but hopelessly confused debate. Three categories of questions are being asked. They must be separated to be clearly understood.

1. By what right does the president order the killing by drone of enemies abroad? What criteria justify assassination?

Answer: (a) imminent threat, under the doctrine of self-defense, and (b) affiliation with al-Qaeda, under the laws of war.

Imminent threat is obvious. If we know a freelance jihadist cell in Yemen is actively plotting an attack, we don’t have to wait until after the fact. Elementary self-defense justifies attacking first.

Al-Qaeda is a different matter. We are in a mutual state of war. Osama bin Laden issued his fatwa declaring war on the United States in 1996; we reciprocated three days after 9/11 with Congress’ Authorization for Use of Military Force – against al-Qaeda and those who harbor and abet it.

Regarding al-Qaeda, therefore, imminence is not required. Its members are legitimate targets, day or night, awake or asleep. Nothing new here. In World War II, we bombed German and Japanese barracks without hesitation.

Unfortunately, Obama’s Justice Department memos justifying the drone attacks are hopelessly muddled. They imply that the sole justification for drone attack is imminent threat – and whereas al-Qaeda is plotting all the time, an al-Qaeda honcho sleeping in his bed is therefore a legitimate target.

Nonsense. Slippery nonsense. It gives the impression of an administration making up criteria to fit the president’s kill list. No need to confuse categories. A sleeping Anwar al-Awlaki could lawfully be snuffed not because of imminence but because he was self-declared al-Qaeda and thus an enemy combatant as defined by congressional resolution and the laws of war.

2. But Awlaki was no ordinary enemy. He was a U.S. citizen. By what right does the president order the killing by drone of an American? Where’s the due process?

Answer: Once you take up arms against the United States, you become an enemy combatant, thereby forfeiting the privileges of citizenship and the protections of the Constitution, including due process. You retain only the protection of the laws of war – no more and no less than those of your foreign comrades-in-arms.

Lincoln steadfastly refused to recognize the Confederacy as a separate nation. The soldiers that his Union Army confronted at Antietam were American citizens (in rebellion) – killed without due process. Nor did the Americans storming German bunkers at Normandy inquire before firing if there were any German-Americans among them – to be excused for gentler treatment while the other Germans were mowed down.

3. Who has the authority to decide life and death targeting?

In war, the ultimate authority is always the commander in chief and those in the lawful chain of command to whom he has delegated such authority.

This looks troubling. Obama sitting alone in the Oval Office deciding what individuals to kill. But how is that different from Lyndon Johnson sitting in his office choosing bombing targets in North Vietnam?

Moreover, we firebombed entire cities in World War II. Who chose? Commanders under the ultimate authority of the president. No judicial review, no outside legislative committee, no secret court, no authority above the president.

OK, you say. But today’s war is entirely different: no front line, no end in sight.

So what? It’s the jihadists who decided to make the world a battlefield and to wage war in perpetuity. Until they abandon the field, what choice do we have but to carry the fight to them?

We have our principles and precedents for lawful warmaking, and a growing body of case law for the more vexing complexities of the present war – for example, the treatment of suspected terrorists apprehended on U.S. soil. The courts having granted them varying degrees of habeas corpus protection, it is obvious that termination by drone is forbidden – unless Congress and the courts decide otherwise, which, short of a Taliban invasion from New Brunswick, is inconceivable.

Now, for those who believe that the war on terror is not war but law enforcement, (a) I concede that they will find the foregoing analysis to be useless and (b) I assert that they are living on a different and distant planet.

For us earthlings, on the other hand, the case for Obama’s drone war is clear. Pity that his Justice Department couldn’t make it.

© 2013, The Washington Post Writers Group