The war against terror is seen by many observers as a foreign policy success for President Obama. But was it legal to kill the Yemeni al Qaeda leader Anwar al-Awlaki and his companion Samir Khan, both American citizens?

A Washington Post editorial today calls the killing “justifiable” and a news story in the paper quotes an Obama Administration official saying that “what constitutes due process in this case is a due process in war.”

Andrew Sullivan on his blog, The Dish, is of a similar view:

“My own position is that we are at war, and that avowed enemies and traitors in active warfare against the U.S. cannot suddenly invoke legal protections from a society they have decided to help destroy.”

I tend to agree, but the issue is not simple, it’s not black and white.

And many are concerned, like Glenn Greenwald at the web site Salon, who condemns the killing. It now appears, he writes, that American citizens can be killed without due process of the law.

Yale law Professor Stephen L. Carter writes on the Daily Beast that the attack raises important ethical questions.

“Obama should tell us, clearly and simply, what the goal of the drone war is; what ethical rules guide him in deciding whom to target; and how we will know when the war is won.”