Clearly, the nature of our military challenges is different in the twenty-first century, and our force structures have to adapt to those needs. In today’s security environment, we must be prepared to deal with a full range of contingencies, with forces that are qualitatively different from those of the twentieth century. But America’s ability to deliver military force across the globe to meet these contingencies cannot be allowed to deteriorate in the face of serious threats to U.S. vital interests. That America’s ability to do so would be compromised by arbitrary budget sequestration decisions void of strategic content is unconscionable.

Military activity and diplomacy are not mutually exclusive. In modern conflicts they are increasingly intertwined, and military activity can be an enabler of diplomacy. As former British Army officer Emile Simpson wrote in War from the Ground Up: Twenty First Century Combat as Politics, “military activity is not clearly distinguishable from political activity.”

At the same time, the military instrument is a means to political ends—military victory has never been an end in itself. As the Tet Offensive began in Vietnam in 1968, General William Westmoreland lamented that the North Vietnamese were “trying to win politically what they could not militarily,” which proved to be a telling statement as to why the United States could never win in Vietnam. Many decades later, military success in deposing the Taliban in Afghanistan, Saddam Hussein in Iraq, and Muammar Gaddafi in Libya did not achieve the political outcomes they were designed to enable; military victory was a necessary but hardly sufficient ingredient to strategic success.

To be sure, the military is not always the right instrument. As President Obama noted in a commencement address at West Point in 2014, “The military ... is, and always will be, the backbone of [our] 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.”

After Vietnam, the U.S. was reluctant to employ military force to achieve political ends. Our uniquely stunning success in Iraq in 1990-91 produced a renewed enthusiasm—and perhaps exaggerated expectations—about the use of military force. Over the past decade, public opinion has again reflected a deep reticence to commit American lives and treasure unless there is a clear danger to American vital interests and the prospect of near-term success.

In reality, the answer cannot reflect either extreme, based on the public’s enthusiasm for committing military force. Government must lead, engaging public opinion with an honest appraisal of the stakes as well as the risks involved. We must debate so we can commit ourselves with one voice. We must be consistent with our principles and conform to our standards within the rule of law. And we must have a realistic understanding of the limits of military force and how force and diplomacy can be employed synergistically to achieve our political objectives.

Our world has no small number of brutal dictators leading failed or failing states, or deadly megalomaniacs leading terrorist organizations, openly violating international norms and basic human rights and threatening U.S. interests.

But does that mean that the U.S. has the responsibility—even if it has the capacity—to intervene with military force? Conflicts are often also local, between competing ethnic or religious claims, or tribal rivals fighting over resources. If we interpose ourselves in local rivalries—ancient or modern—we run the risk of transforming second or third order conflicts fought with antiquated weapons into full blown deadly wars fought with modern high technology weapons that could destroy whole populations. We must also avoid the belief that we can simply impose our concepts of governance on societies that long predate our own, and then depart.

We offer, therefore, the following essential principles for employing military force:

- We must honor our treaty commitments.

- We should engage when our vital interests are directly threatened. When we do, we must define clearly what military victory looks like and how it contributes to the achievement of political objectives. And then we must fight to win.

- We should intervene in the aftermath of natural disasters to help those affected and to facilitate the reestablishment of effective and responsible governance.

- We should intervene in the face of humanitarian crises, but not if our actions will simply create a political vacuum that exacerbates the crisis.

- If we intervene, we should be prepared to commit—with international partners—to enable a transition to responsible governance. If we are not prepared to do this, then we should not intervene.

Not all national security problems can be solved. Sometimes they can only be managed, and their deleterious effects perhaps minimized. When one cannot coerce, one must be patient, just as George Kennan famously advocated in his outline of America’s Cold War “containment” doctrine in 1947. America’s reluctance to use military force does not mean disengagement. It means that we must deal with others on their own terms and be prepared to engage through diplomacy. That takes time, and it necessarily involves compromise, but it has shown itself to be a much more reliable and sustainable instrument than coercion.

Ultimately, military force—whether as a credible threat or through actual use—remains an important complement to political action. Whatever national security strategy the next Administration chooses to pursue must reflect a sophisticated understanding of how today’s various and diverse instruments of military force are integrated with non-military means to achieve political ends.

The bottom line...

American global leadership is important—not only because others look to us, but also because it is in our interests and within our responsibility if we are to live up to the values we profess. How we lead, however, matters, because this world does not enable us to dictate outcomes. Not only are our resources limited, but others also have—and we need them to have—a stake in the system.

We must stand firm against those who would wreak havoc within the system, but we will have our greatest success if we can engage others in ways that encourage them to invest in the system. This, however, requires that they also have a voice in shaping that system. This will also offer us the broadest base of support if we have to use military force as an essential enabler to effective diplomacy.

Ultimately, America’s legitimacy as a global leader will rest not only on our military and economic power, but also on the moral authority that we garner by being a nation committed to the principles of our founding and the rule of law. If we cannot harness those institutions to the service of our national enterprise, we will surely find ourselves in decline, isolated, and our national security severely challenged on many fronts.

Dr. Schuyler Foerster is a retired U.S. Air Force officer and taught at the U.S. Air Force Academy as the Brent Scowcroft Professor for National Security Studies. He currently is principal of CGST Solutions, a consulting company that specializes in security policy and civic education. Dr. Ray Raymond is a former British Diplomat, now Professor of Government and History at the State University of New York Stone Ridge. He is also Adjunct Professor of Comparative Politics and International Relations at the U.S. Military Academy at West Point.

Image: The crew of USCGC Kiska fly a battle ensign upon completion of a patrol. Flickr/U.S. Coast Guard.