Driving through my hometown recently, I passed half a dozen neighbors holding antiwar signs. One declared, "BRING ALL OUR TROOPS HOME," with "ALL" underlined. I honked and gave them a thumbs-up. Like many doves, I'm glad that the U.S.—after eight bloody years and the deaths of 4,500 Americans and tens of thousands of Iraqis—has finally withdrawn its armed forces from Iraq. But I'd like to see my country take much bolder steps toward peace, not only for Americans but all people. As I argue in The End of War--which is being published today and has already received attention from MSNBC, the Israeli newspaper Haaretz, the Cleveland Plain Dealer and The Chronicle of Higher Education--our goal should be to eradicate war and even the threat of war among nations.

Humanity is, according to some measures, headed in the right direction. Since the cataclysm of World War II, there have been no comparable wars among major powers. The Cold War, along with the threat of global nuclear annihilation, ceased without bloodshed two decades ago. Since then, the number of international wars and civil wars has declined, and combat casualties have plummeted. The psychologist Steven Pinker and political scientist Joshua Goldstein, authors of books on the decline of armed conflict, proposed last month in The New York Times that war may be "going out of style."

I share this optimism, with one big caveat: The U.S., which continues to cling to the atavistic adage that peace can only be assured by fighting and preparing to fight, remains a major impediment to a post-war world. We insist that we are a peaceful people, and yet we maintain a global military empire, with soldiers deployed in more than 100 countries. In the past decade we have been embroiled in two major wars, in Iraq and Afghanistan, as well as contributing to the recent bombing campaign against Libya.

Consider, moreover, these statistics from SIPRI, the Stockholm International Peace Research Institute, a respected, independent tracker of trends in conflict. The U.S. military budget has almost doubled in the past decade to $700 billion. If you include spending on nuclear weapons and homeland security, our annual outlays approach $1 trillion, which exceeds the defense budgets of all other nations combined. We spend more than six times as much on defense as China, our closest competitor, and more than 10 times as much as our former nemesis Russia.

The U.S. is also by far the world's largest arms dealer. Our weapons sales, which according to SIPRI came to $247.2 billion in 2009, surpass those of all other nations put together. Just in the past month, U.S. officials signed off on fighter-plane sales of $29.4 billion to Saudi Arabia (a deal announced on Christmas Eve!) and $7 billion to Japan. The U.S. has also pledged to transfer $11 billion in tanks and other weapons to Iraq's fledgling government. Some security analysts fear that these latter weapons, rather than maintaining the peace there, will simply help the Shiite-dominated government crush Kurds, Sunnis and other rivals for power.

The chasm between our nation's rhetoric and behavior is embarrassing. We rail against Iran for allegedly trying to build a nuclear bomb while we maintain a stockpile of 8,500 warheads. We denounce tyrants such as Libya’s Muammar Qaddafi and Syria's President Bashar al-Assad for killing civilians, and yet our own military operations in Afghanistan and elsewhere often result in the deaths of innocent people. We carry out drone and commando assassinations in other countries, in defiance of international prohibitions against assassinations, and we imprison suspected enemies indefinitely without a trial. And yet we bristle when observers call us hypocrites.

We could help lead the entire world toward a more peaceful future if we backed up our dovish words with actions. For starters, we should cut our military budget in half, a level that would still be greater than the military spending of China and Russia combined. (The measly reductions recently proposed by the Obama administration, which would reduce by the budget by less than 10 percent over the next decade, are not nearly enough.) We should start recalling our troops from Afghanistan and other nations and stop peddling arms overseas. We should cease assassinating people with our robots and commandos. In tandem with these steps, we should seek more creative ways to prevent and suppress armed conflicts nonviolently.

Of the current crop of U.S. presidential candidates, only one, Texas Congressman Ron Paul, advocates deep cuts in our armed forces. Even disregarding Paul's opposition to social safety nets such as Social Security and Medicare, which I view as triumphs of enlightened governance, I will not vote for him. My main objection to Paul is that he is too isolationist; he advocates pulling out of the United Nations, which in spite of its flaws helps reduce armed conflicts around the world through its diplomacy and peacekeeping operations.

Paul's rivals for the Republican nomination, far from advocating reductions in defense spending, have called for increases. And Barack Obama has not exactly become the Peace President that many of us hoped for. In fact, while accepting the Nobel Prize for Peace two years ago—just nine days after he announced that he was sending 30,000 more American troops to Afghanistan—Obama seemed to suggest that war is a permanent part of the human condition. He declared that "war, in one form or another, appeared with the first man" and that "we will not eradicate violent conflict in our lifetimes."

Our leaders—and would-be leaders—should repudiate this sort of fatalism. For inspiration, they might re-read a speech that President John F. Kennedy gave at American University in 1963, just months before his death. Kennedy pledged his commitment to the goal of "world peace," which he defined as "not merely peace for Americans but peace for all men and women—not merely peace in our time but peace for all time." He urged his young audience to reject the "dangerous, defeatist belief" that "war is inevitable, that we are gripped by forces that we cannot control. We need not accept that view. Our problems are manmade—therefore they can be solved by man." Demonstrating his sincerity, Kennedy announced that the U.S. would cease testing nuclear weapons in the atmosphere.

With this sort of courageous, visionary leadership, the U.S. can help make war between nations not only improbable but also inconceivable, as much so as war is now between Canada and the U.S., or even between New York and New Jersey. Most people find this scenario implausible, even impossible. But far from being a utopian fantasy, ending war should be a moral imperative.