One of the primary beliefs held by the Washington foreign policy establishment for decades is that U.S. “leadership” in the world has been essential to the development of international order and the preservation of international peace.

Defenders of U.S. primacy insist that the world would devolve into chaos and violence if the United States reduced its expansive foreign policy ambitions, and that the only thing holding back the return of the so-called “jungle” is American power. John Mueller takes a sledgehammer to these and other lazy assumptions in his outstanding new book, “The Stupidity of War.” He contends that the strong aversion to international war since 1945 has had more to do with preventing another world war than the development of nuclear weapons or U.S. security guarantees, and he makes a compelling case that this is the cause of the “long peace.”

Mueller goes on to show that Washington has consistently exaggerated foreign threats and overestimated the need for militarized responses to threats that were minimal or non-existent, going all the way back to the earliest days of the Cold War. He persuasively argues the case for what he calls complacency and appeasement: the United States faces few real threats, most of them will diminish or implode before they become a serious problem, and most of the threats that policymakers obsess over are manageable or imaginary. He also challenges one of the central myths about the “liberal international order” by denying that an ambitious U.S. grand strategy was necessary to secure the benefits of postwar democratization and economic growth.

Even if you don’t accept every one of his claims, Mueller has made a powerful case for the virtues of doing far less in the world militarily and exercising restraint in the face of provocations. “The Stupidity of War” makes for bracing reading, and it will force readers from all foreign policy camps to reconsider what they think they know about the history of U.S. foreign policy.

He doesn’t ignore cases that complicate his overall argument, and he acknowledges that there are some occasions where small U.S. military interventions have achieved limited goals. He grants that the small invasions like the interventions in Grenada and Panama in the 1980s qualify as successful uses of force. His willingness to acknowledge the very few exceptions to the rule of postwar U.S. military failure abroad makes his main argument that much stronger.

 Simply put, most wars are stupid and wasteful, and they should be avoided.

 This is particularly true for the United States, which has the advantage of being extraordinarily secure from physical threats. Even at the height of the Cold War, the actual threat from the Soviet Union was far less than what policymakers imagined, and foreign threats in the last 30 years have been even smaller.

While most advocates for a less aggressive U.S. foreign policy might shy away from the word appeasement, Mueller reclaims the term to restore it to its original meaning. Appeasement has been a curse word hurled against opponents of militaristic policies for the last 75 years because of the unusual events of the late 1930s. It described the efforts of Britain and France at that time to resolve international disputes through diplomatic negotiations to avoid another great war, and because this failed in the face of Hitler’s revanchist aggression, the word has been used to discredit diplomatic compromises ever since.

As Mueller points out, it was appeasement that averted catastrophe in the 1962 Cuban Missile Crisis, which had the potential to lead to a global conflagration even more murderous than World War II. In general, he says, appeasement succeeds in avoiding stupid wars, and avoiding stupid wars is in the best interests of all concerned.

Hawks continue to conjure up the specter of Munich to justify their preferred policies, but the horrors of WWII already instructed the world in the insanity of wars between the major powers. We should be far less worried about appeasing a would-be aggressor and much more concerned about a militarized foreign policy that overreacts to every possible danger.

“Complacency and appeasement, then, have much to recommend themselves,” Mueller writes, and he is right. U.S. foreign policy has been driven for decades by alarmism and worst-case scenarios, and that has produced militarized excesses that have produced almost uniformly horrible results for the United States and the affected countries. It is long past time that we adopted a very different approach to how our government assesses and responds to potential threats.

The practical implications of Mueller’s argument are straightforward. If the threats to the United States are so few and manageable, there is no need for vast military spending and such a large military. Instead of seeking monsters to destroy, Mueller advises the United States to be patient and wait for the worst regimes to collapse from their own inherent weaknesses. The conceit of defenders of the “liberal international order” is that the current level and projection of American power is essential to maintaining it, and Mueller demonstrates that it simply isn’t so. The U.S. pursuit of global dominance isn’t necessary for our security, and it isn’t essential to maintaining so-called world order, either. It makes no sense for us to do what we have been doing for decades, and we could stop without major adverse consequences.

There are a few comments in the book that may strike restrainers as odd, but they don’t undermine the larger argument. For instance, Mueller repeatedly refers to Iran’s nuclear weapons program as if this were something that still existed at the time of the nuclear negotiations leading to the Joint Comprehensive Plan of Action. No such program existed in the 2010s, and it hadn’t existed since at least 2003. Acknowledging this fact would strengthen Mueller’s larger point that proliferation fears in Washington are overblown. Iran wasn’t seeking to build a nuclear weapon before it agreed to the restrictions contained in the 2015 agreement, and it isn’t seeking to build one now despite their government’s reduced compliance with the agreement in response to U.S. sanctions. An “Iranian bomb” has been an imaginary danger for a long time, and hawks have stoked fears of this possibility to justify continued hostility towards Iran.

One of the most important points that Mueller makes is that the actual costs of wars of “counter-proliferation” have been vastly more expensive and destructive than the proliferation dangers that they were supposed to prevent. The Iraq war is the prime example of this. A war that was sold primarily in terms of eliminating weapons of mass destruction programs ended up killing hundreds of thousands of people and destabilizing the region for years to come. Even if Iraqi unconventional weapons programs had still existed at the time of the invasion, the war would still have been unnecessary and, yes, very stupid. The ongoing obsession with Iran’s evidently peaceful nuclear program shows that most policymakers in Washington still haven’t learned one of the most important lessons of the Iraq war, namely that the possibility of future nuclear proliferation is not so dangerous that it warrants waging a disastrous preventive war.

War is a waste, and diplomacy, or “appeasement,” as Mueller might put it, is often the correct response to difficult international disputes. The post-WWII international order was built on these assumptions, but our policymakers have done a poor job of following them for the last seven decades. Instead of constantly being on the lookout for new monsters to destroy, the U.S. needs to stop imagining threats that aren’t there.