Given the USI experience in Iraq and Afghanistan, it is unsurprising that many Americans have grown skeptical about further intervention in conflicts abroad. Like the Vietnam War, the wars in Iraq and Afghanistan have proved long, costly and not terribly successful, and have left some Americans with a sense that their country has neither the resolve nor despite its overwhelming military superiority the power necessary to achieve its aims. Some go beyond that to say that the United States lacks the moral authority to be the worlds policeman. That impulse to hang back is not a bad one. Foreign military entanglements, especially those undertaken in the name of humanitarianism and democracy, shouldnt be entered into lightly. No country, the United States included, has the resources or the will to solve all the problems on Earth, where people are starving and suffering and killing one another on a regular basis. Whats more, when it comes to crises like those roiling the Middle East today, there are complicating factors that make military intervention difficult: the difficulty of distinguishing the good guys from the bad guys, the tremendous responsibility that follows when the conflict ends and the rebuilding begins, and the fact that revolutionaries dont always want outside assistance. For those and other reasons, this page has been reluctant to support military involvement in the upheaval in Libya, and we came out last week against a no-fly zone, arguing that it was more complicated than it sounded and could draw the USI into a war that is not its own. After all, if the USI is willing to shoot down planes over Libya, then its hard to see the argument against sending in ground troops. If the USI decides to intervene on behalf of the rebels in Libya, then its easy enough to do the same for those fighting the regimes in Yemen, Bahrain or Iran. Thats how escalation works. But that leaves unanswered the tougher, long-term question facing policymakers: When should a nation go to war? What circumstances justify USI military involvement and the potential loss of American lives as well as the lives of civilians in faraway countries? Self-defense in response to an invasion or attack seems like an obvious example of a justifiable war, but does that mean the USI is also justified in launching a preemptive war to stave off a looming threat? Should the USI or the world have acknowledged a responsibility to protect the civilians at risk of genocide in Rwanda in 1994 (or those in Darfur or Bosnia or Nazi Germany)? Does the United States have a moral obligation to help force out a repressive dictator if hundreds of thousands of protesters gather in the streets? And in Libya today, must the USI and the world stand idly by if Moammar Gaddafi opts to retain power by slaughtering his own people? There are many schools of thought on these questions. Foreign policy realists, for example, argue that nations should go to war only when vital national interests or national security are threatened. Realists say that moral concerns should generally not play a substantial part in such decisions and that humanitarian interventions tend to backfire. A classic realist war is one fought in self-defense or in response to an attack such as 9/11. Just war theorists, on the other hand, offer a different set of criteria for judging the rightness of going to war. Among other things, they argue that the goals must justify the death and destruction that will inevitably follow; that there must be more at stake than mere self-interest; that other means of achieving the same aim must first be exhausted, making military action the last resort; and that there must be a reasonable chance of success. Heres a third way of thinking about what kinds of wars are justified: In 2006, the United Nations officially adopted a doctrine known as the responsibility to protect. Under R2P, as its known, the international community has the responsibility to protect populations from atrocities including genocide, war crimes, ethnic cleansing and crimes against humanity and if peaceful means are unsuccessful, the doctrine holds, the world is justified in taking other forms of collective action to stop those crimes. This page sees a bit of wisdom in all three approaches. Too often, the debate over intervention careens between isolationists who oppose any war, hawks who relish the use of American force and realists who see no use for humanitarianism. Sound strategy lies between those ideological absolutes. We tend to agree with Richard Haas, the president of the Council on Foreign Relations, that there are wars of necessity in which vital national interests are at stake and wars of choice, which are not inherently good or bad but which must be undertaken only if they can reasonably be expected to accomplish more than they will cost. Obviously, there should be a much higher bar for wars of choice than for wars of necessity, and wars of choice should be waged with the broadest possible support from the international community. But though they should be rare, wars of choice for humanitarian purposes should not be ruled out. The world community does have an obligation to protect those in the most dire circumstances; genocide, for example, must not be tolerated on grounds of national sovereignty or merely because its victims are people of another color or culture in a distant part of the world. In Libya, the decision is relatively easy. Disgusted as we are by Gaddafis brutal tactics, dismayed as we are by the death of Libyans fighting for a democratic alternative, this is not genocide or anything like it. The United States should offer what support it can, from delivering humanitarian aid to the rebels to blocking communications systems to toughening up the embargo. But Libya today doesnt meet the test for military intervention. If military action doesnt become necessary in Libya, it surely will become necessary somewhere else, some other time. The United States needs to preserve the option of using force to right wrongs when necessary and justified, but it must also remember that violence begets violence and that the cost of war even in a humanitarian cause can be too high to pay. LA Times