Take some recent examples. In large part, the 1991 Persian Gulf war was about exerting power: It sought to prevent an invasion of Saudi Arabia and oust Iraqi forces from Kuwait. However, in Vietnam, the end goal was political influence: The war was fought to keep the south from falling to the communists. The examples are just two among many, but interestingly, they are illustrative of when war works, and when it doesn't.

Indisputable is the fact that war is the most powerful weapon in the foreign policy arsenal, but looking closer it's clear that war may also be the most limited. According to a new investigation by two political scientists, since World War II, the major powers -- Russia, France, China, England, and the U.S. -- have launched 126 foreign military interventions. Viewed together, it's clear that to project power, yes, war works. But to pursue political ends (an entirely different goal), war is a largely deficient means. Consequently, the engineers of American foreign policy would be wise to consider that exerting influence within an international order that more and more turns on political interventions and less and less on state-based conflict means less conquering the enemy with warfare and more engagement by innovative and constructive means.

First, power and politics have to be understood as being separate and distinct. The new study in the Journal of Peace Research by Patricia Sullivan and Michael Koch measured the outcomes of 126 wars waged by the great powers since World War II against the original political aims for which they were launched. In terms of the gross extension of power -- overthrowing a foreign government or defending an ally from an impending threat, for instance -- war worked almost all the time. (Think 1991 Persian Gulf.) However, when the end goal was imposing politics, not even a third of the missions were successful. (Think Vietnam.) According to Sullivan and Koch, "Major power states are least likely to be successful when they attempt to coerce a foreign government into changing its foreign or domestic policy."

Such has been the case, without falter or much variation, for the last 60 years: war for power wins, war for politics loses. The conclusion is shocking for two reasons. First, some have suggested that more recently the major powers are subject to their people being increasingly affected by the horrors of battle -- the result of the CNN-effect, which brings the horrors of war to the dinner table. Second, the phrase "since the end of the Cold War . . . " has become almost ubiquitous in international relations thinking for the last three decades. At least according to Sullivan and Koch's newest study, neither has had much effect on the effectiveness of war.

So, what if the American foreign policy establishment conceded that, for today's world, war doesn't work? In some sense, such a realization has already begun. The new counterinsurgency and stability operations manuals are clear moves by the military away from state-based industrial war to the reality of what the U.S. military has been doing in Somalia, Haiti, Bosnia, Kosovo, Iraq and now Afghanistan, what Rupert Smith calls "war amongst the people." But military brass -- as well as Congress and the White House -- have still not resolved the core dilemma -- that carrying a gun makes for bad politics.

In turn, Secretary of State Hillary Clinton's "smart power" sounds like the smartest thing around. Smart power employs the "three Ds." It would be a way of creating incentives (development), negotiating politics (diplomacy), and having force at your disposal (defense). Exactly how and where smart power would work remains to be seen, but it's at least thinking in the right direction.

As it stands now, many of the carrots and sticks are coming up short. Iran seems to be moving forward on developing a nuclear weapon; North Korea is already there. Sanctions, as a tool of the United Nations Security Council, can be a deterrent, but as an inducement mechanism they are also riddled with problems. So we're left with a confounding dilemma -- as war proves less and less effective in combating global threats, we're short on other tools. Meanwhile, the defense budget keeps growing. Until the reality sinks in, the problem grows more and more intractable.

**Andrew Bast has reported from four continents for several publications, including Newsweek and the New York Times.