Like Eisenhower, this generation of men and women in uniform know all too well the wages of war, and that includes those of you here at West Point. Four of the service members who stood in the audience when I announced the surge of our forces in Afghanistan gave their lives in that effort. A lot more were wounded.

I believe America’s security demanded those deployments. But I am haunted by those deaths. I am haunted by those wounds. And I would betray my duty to you, and to the country we love, if I sent you into harm’s way simply because I saw a problem somewhere in the world that needed to be fixed, or because I was worried about critics who think military intervention is the only way for America to avoid looking weak.

Here’s my bottom line: America must always lead on the world stage. If we don’t, no one else will. The military that you have joined is, and always will be, the backbone of that leadership. But U.S. military action cannot be the only, or even primary, component of our leadership in every instance. Just because we have the best hammer does not mean that every problem is a nail.

And because the costs associated with military action are so high, you should expect every civilian leader — and especially your commander in chief —to be clear about how that awesome power should be used. So let me spend the rest of my time describing my vision for how the United States of America, and our military, should lead in the years to come, for you will be part of that leadership.

First, let me repeat a principle I put forward at the outset of my presidency: The United States will use military force, unilaterally if necessary, when our core interests demand it: when our people are threatened; when our livelihoods are at stake; when the security of our allies is in danger.

In these circumstances, we still need to ask tough questions about whether our actions are proportional and effective and just. International opinion matters, but America should never ask permission to protect our people, our homeland or our way of life. (Applause.)

On the other hand, when issues of global concern do not pose a direct threat to the United States, when such issues are at stake, when crises arise that stir our conscience or push the world in a more dangerous direction but do not directly threaten us, then the threshold for military action must be higher. In such circumstances, we should not go it alone. Instead, we must mobilize allies and partners to take collective action. We have to broaden our tools to include diplomacy and development, sanctions and isolation, appeals to international law, and, if just, necessary and effective, multilateral military action. In such circumstances, we have to work with others because collective action in these circumstances is more likely to succeed, more likely to be sustained, less likely to lead to costly mistakes.