Last December, President Obama gave two speeches on war. His West Point speech outlined his troop increase in Afghanistan and a deadline of summer 2011 to begin withdrawal. A few days later, he went to Oslo to accept the Nobel Peace Prize.

Obama’s Nobel speech surprised many who thought they had finally found a president of the United States willing to tell Americans to lay down their arms and just talk problems out, the rational and enlightened way. Obama did indeed denounce violence, and he’s talked on occasion with implacable foes. But in Oslo, he defended the use of force on some occasions because, as he said, “Make no mistake: Evil does exist in the world.” Many Europeans had not heard the word “evil” since Obama’s loathed predecessor described the existence of an Iran-Iraq-North Korea axis thereof. Staying with his theological and philosophical theme, he gave us some intellectual history:

And over time, as codes of law sought to control violence within groups, so did philosophers and clerics and statesmen seek to regulate the destructive power of war. The concept of a ‘just war’ emerged, suggesting that war is justified only when certain conditions were met: if it is waged as a last resort or in self-defense; if the force used is proportional; and if, whenever possible, civilians are spared from violence.

Obama favors the work of theologian Reinhold Niebuhr, who was interested in just war theory as part of his “Christian realism.” But for a president to set himself the standard of paying close attention to just war principles as he considers military decisions is to set a high level for White House discourse. Many presidents have thought about such issues, and all have justified their commitments to military action on moral grounds. But few, if any, have spelled out just war theory in public as the basis for decision-making.

Now we get Bob Woodward’s new book, Obama’s Wars. How has Obama done in actually applying just war principles? Take Obama’s own simple, tripartite explanation of when war is just as the model:

Last resort/self-defense. Obama apparently thinks war is the last resort for 18 months before a deadline, or until some level of fiscal pain is felt, but not after that. Obama also told Woodward this: “I think about it not so much in the classic, do you lose a war on my watch? I think about it more in terms of, do you successfully prosecute a strategy that results in the country being stronger rather than weaker at the end of it?” So his strategy is aimed to make us stronger, somehow, but not at using force to achieve military victory where no other means is available. This is not self-defense; it’s community organizing on a grand scale.

Proportionality. This principle is usually applied in association with one Obama didn’t mention, that there has to be a reasonable likelihood of success. Woodward’s book suggests that Obama is unsure that success can be had, or even what it looks like. He appeared personally to favor a more immediate withdrawal and a much smaller force commitment. He dictated a lengthy terms sheet to make sure his military leaders did not expand the mission (though the military had its own doubts about defeating the Taliban). Obama’s proportionality judgment has much to do with not losing the entire Democratic party and not getting into “another Vietnam,” less to do with determining whether the war is proportionate to its expected gains. With Option A as quick withdrawal and minimal force, and Option C as a high force commitment to better ensure success, he chose Option B. But “in-between” is not necessarily “just.”

Sparing civilians where possible. We’ll give Obama this one, with one caveat — going into a war as a short-term experiment generally fails and saves few lives, military or civilian, in the long run.

Applying just war principles is hard in the messy real world, and Afghanistan is as tough a case as one could imagine. But that doesn’t mean just war principles are wrong. Obama’s Nobel speech was a high-minded moment. He would have done better to keep just war principles in mind at the moment of decision.

– Joseph R. Wood is a senior resident fellow at German Marshall Fund of the U.S. The views here are his own.