During the Cold War, there was good reason for the United States to act as the world’s policeman. It was a bipolar world with two competing military superpowers—America and the Soviet Union. America’s allies were relatively weak because they were still recovering and rebuilding their economies in the wake of World War II. As such, the U.S. needed to be omnipresent around the world to keep Soviet expansionism in check because security was seen as a zero-sum game: a gain by one side was a commensurate loss by the other.

America is still a superpower, but the world has changed and is now multi-polar. Russia is still a major power, but not the same threat as the former Soviet Union. China is a rising regional power with perhaps further aspirations, so America must watch its ascension closely. Yet the U.S. engages in economic exchange with both Russia and China—as such, they are not mortal enemies.

Communism still exists, but it isn’t necessarily expansionist and a threat to the U.S. and other democratic nations—so it’s not a zero-sum game like it once was.

All these and other changes in the world demand we reexamine whether what most people agree worked from the end of WWII through the ’80s and early ’90s continues to make sense in a post-Cold War world.

To begin, being the world’s policeman should have a direct connection to U.S. security. Since the fall of the Berlin Wall, the U.S. has employed significant military force over the course of five different administrations. But only one of those—Operation Enduring Freedom in Afghanistan—was as a result of a direct threat to U.S. national security.

Then there is the question of what it costs us. Even before Operation Iraqi Freedom, more than 240,000 U.S. troops were either stationed in foreign countries or at sea in other regions of the world. With an all-volunteer force, maintaining these levels requires at least twice as many additional troops to be deployed in the United States so that the overseas force can be rotated at specified intervals. That means more than 700,000 active-duty military personnel to be the world’s policemen. And it’s worth noting that manpower costs and the costs of operating and maintaining all the equipment for that manpower are more than 60 percent of the Pentagon’s budget. So, the American taxpayer is paying a considerable sum for the U.S. military to police the world.

Another cost of the U.S. policing other countries’ security is the wear and tear on the U.S. military. Military operations in Afghanistan and Iraq—as well as Libya and Syria—have only exacerbated prior decades of unnecessary military interventions. The result is a so-called readiness crisis, otherwise known as the hollowing out of the military. The cost to buy back readiness is debatable. Some, such as the House Armed Services Committee, put the price tag as high as $1 trillion.

During the Cold War, the U.S. had little choice but to bear the costs. But now, our allies are in a position where they can and should share the burden of defense, taking primary responsibility for policing their own neighborhoods. The United States’ Gross Domestic Product (GDP) is a little more than $16 trillion. The rest of NATO’s GDP is slightly less than $20 trillion, more than $18 trillion of which comes from Europe.

Europeans, who view Russia as a threat they must confront, have the wherewithal to do so. NATO’s European countries’ economies eclipse Russia’s by more than 10-to-1, and NATO Europe outspends Russia—$250 billion versus $66 billion—by a margin of nearly 4-to-1 on defense.

Similarly, both Japan and South Korea can afford to shoulder the primary burden for their defense. Japan has the third-largest economy in the world with a $4.1 trillion GDP, and South Korea has the 11th-largest with a $1.4 trillion GDP—combined, more than 300 times larger than North Korea’s $16 billion GDP. And the combined economy of Japan, South Korea, Taiwan, Australia, New Zealand, the Philippines, Vietnam, Malaysia, Thailand, and India is on the order of $12 trillion, which compares favorably to China’s $14 trillion economy.

This is not to say that the U.S. should abandon allies and retreat from the world—far from it. More engagement and trade are long overdue. But rather than being the world’s policeman and primary balancer of power, in a multi-polar world, the United States can and should allow countries in each region to establish their own balance-of-power arrangements. The U.S. would still be committed to security in those regions, but as a balancer of last resort—intervening if, and only if, the nations in the region cannot contain the situation.

A balancer-of-last-resort strategy is a more realistic approach in a multi-polar world because it would allow the United States to distinguish between crises and conflicts vital to its interests and those that do not threaten U.S. national security—rather than assuming that every crisis requires U.S. military intervention.

Charles V. Peña is a senior fellow with Defense Priorities. He has more than 25 years of experience as a policy and program analyst and senior manager, supporting both the Department of Defense and Department of Homeland Security. Peña is the former director of defense-policy studies at the Cato Institute and author of Winning the Un-War: A New Strategy for the War on Terrorism