So yes, the instruments of war do have a role to play in preserving the peace. And yet this truth must coexist with another — that no matter how justified, war promises human tragedy. The soldier’s courage and sacrifice is full of glory, expressing devotion to country, to cause, to comrades in arms. But war itself is never glorious, and we must never trumpet it as such.

So part of our challenge is reconciling these two seemingly inreconcilable truths — that war is sometimes necessary, and war at some level is an expression of human folly. Concretely, we must direct our effort to the task that President Kennedy called for long ago. “Let us focus,” he said, “on a more practical, more attainable peace, based not on a sudden revolution in human nature but on a gradual evolution in human institutions.” A gradual evolution of human institutions.

What might this evolution look like? What might these practical steps be?

To begin with, I believe that all nations — strong and weak alike — must adhere to standards that govern the use of force. I — like any head of state — reserve the right to act unilaterally if necessary to defend my nation. Nevertheless, I am convinced that adhering to standards, international standards, strengthens those who do, and isolates and weakens those who don’t.

The world rallied around America after the 9/11 attacks, and continues to support our efforts in Afghanistan, because of the horror of those senseless attacks and the recognized principle of self-defense. Likewise, the world recognized the need to confront Saddam Hussein when he invaded Kuwait — a consensus that sent a clear message to all about the cost of aggression.

Furthermore, America — in fact, no nation — can insist that others follow the rules of the road if we refuse to follow them ourselves. For when we don’t, our actions appear arbitrary and undercut the legitimacy of future interventions, no matter how justified.

And this becomes particularly important when the purpose of military action extends beyond self-defense or the defense of one nation against an aggressor. More and more, we all confront difficult questions about how to prevent the slaughter of civilians by their own government, or to stop a civil war whose violence and suffering can engulf an entire region.

I believe that force can be justified on humanitarian grounds, as it was in the Balkans, or in other places that have been scarred by war. Inaction tears at our conscience and can lead to more costly intervention later. That’s why all responsible nations must embrace the role that militaries with a clear mandate can play to keep the peace.

America’s commitment to global security will never waver. But in a world in which threats are more diffuse, and missions more complex, America cannot act alone. America alone cannot secure the peace. This is true in Afghanistan. This is true in failed states like Somalia, where terrorism and piracy is joined by famine and human suffering. And sadly, it will continue to be true in unstable regions for years to come.

The leaders and soldiers of NATO countries, and other friends and allies, demonstrate this truth through the capacity and courage they’ve shown in Afghanistan. But in many countries, there is a disconnect between the efforts of those who serve and the ambivalence of the broader public. I understand why war is not popular, but I also know this: The belief that peace is desirable is rarely enough to achieve it. Peace requires responsibility. Peace entails sacrifice. That’s why NATO continues to be indispensable. That’s why we must strengthen U.N. and regional peacekeeping, and not leave the task to a few countries. That’s why we honor those who return home from peacekeeping and training abroad to Oslo and Rome; to Ottawa and Sydney; to Dhaka and Kigali — we honor them not as makers of war, but of wagers — but as wagers of peace.

Let me make one final point about the use of force. Even as we make difficult decisions about going to war, we must also think clearly about how we fight it. The Nobel Committee recognized this truth in awarding its first prize for peace to Henry Dunant — the founder of the Red Cross, and a driving force behind the Geneva Conventions.

Continued here