Stephen Walt lists several of the reasons why the U.S. continues to overcommit itself all over the world:

Fourth, the more weight a country places on credibility, the more likely it is to find itself overcommitted, because it will be tempted to act in places that do not matter in order to convince others that it will act in places that do. Such tendencies will be even more pronounced when a country is convinced that a reputation for strength and resolution is essential to deterring hostile attacks, including those with weapons of mass destruction. Even when leaders recognize that an existing commitment is no longer worth the cost, they may shy away from liquidating it for fear that this will embolden adversaries and invite new challenges.

Fifth, there’s the classic problem of sunk costs. This pathology may not explain why states take on ill-advised commitments, but it does help us understand why they have trouble cutting losses and getting out. As soon as anyone points out that an existing commitment is no longer worth keeping or says it is time to withdraw from a losing war, someone is bound to invoke the expense and lives that have already been sacrificed and claim that these sacrifices will be for naught if one does not “stay the course.”

U.S. policymakers and pundits invoke both “credibility” and sunk costs when they have nothing of value left to say. Max Boot does that this week with a column on possible withdrawals from Syria Afghanistan. For good measure, Boot offered up this justification for endless war:

Think of our Indian Wars, which lasted roughly 300 years (circa 1600-1890), or the British deployment on the North West Frontier (today’s Pakistan-Afghanistan border), which lasted 100 years (1840s-1940s). U.S. troops are not undertaking a conventional combat assignment. They are policing the frontiers of the Pax Americana.

These are remarkably bad examples to choose if the goal is to persuade skeptics that these wars are worth fighting. It is not our place to displace and kill people in other countries until the end of time as part of policing some imaginary “frontier.” Frontiers are made by those that insist on defining everything and everyone beyond them as inferior and/or in need of our influence, and they become an open-ended justification for all manner of atrocities and abuses against the people who happen to be on the wrong side of that divide. It is the habit of warmongers and empire-builders to exaggerate the threats that come from beyond the “frontier,” and they use that same threat inflation to drag their country into one unnecessary conflict after another. Only a neo-imperialist like Boot would think to invoke the British occupation of India as a model for how to conduct foreign policy today, but it is a revealing admission that reminds us that the only thing Boot truly believes in is keeping the U.S. committed to fighting people in their own countries forever.

The problems with endless war are not primarily that it is expensive or unsustainable, though it is both of those things, but that it creates far more enemies than it can ever defeat, it causes our government to make alliances of convenience with countless despicable states and armed groups, it corrupts our political system and our values, and it makes a mockery of the Constitution. Americans are more secure from foreign threats than virtually any other nation in history, and yet we have accepted a policy of perpetual war and perpetual fear of grossly exaggerated threats with very little resistance for the last two decades. Perhaps the biggest reason for U.S. overcommitment and overextension is our tendency to give in to irrational fears that distant, manageable threats are imminent, existential ones.

If “policing the frontiers of Pax Americana” requires endless military deployments and unending wars on the other side of the planet, that tells us that there is no pax in the Pax Americana. It is not the responsibility of our government or any other to police the world for all time, and the sooner that our political leaders recognize how insane it is to make the attempt the better off the U.S. and the “policed” countries of the world will be.

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