In this 15th year of war in Afghanistan, as the United States is becoming further entangled in military conflicts in Iraq, Syria and Yemen, we need a serious debate about whether we want to be permanently at war.

We can start by noting a few simple rules about war and foreign policy. War cannot be avoided at all costs, but it should be avoided wherever possible. Proposals to involve the United States — or any government — in foreign conflict should be treated with great skepticism.

Despite the constant warnings of war hawks, and the ongoing images of conflict on our screens, the world is safer than it’s ever been. And for the United States, the most secure power in world history, protected by two oceans and friendly neighbors, that’s especially true.

The first purpose of government is to protect the rights of citizens. We must maintain an adequate national defense, but we can defend the vital interests of the United States with a military budget about half the size of the one we have — if we reorient our foreign policy to one of self-defense and restraint, not global commitments to collective security agreements.

Libertarians who propose to bring U.S. troops home and concentrate on the defense of the United States are sometimes accused of being isolationist. That’s a misconception.

Libertarians are, in fact, confident and cosmopolitan. We look forward to a world bound together by free trade, global communications and cultural exchange. We support maintaining the world’s largest and most powerful military, by a wide margin, although not as big as the foreign-policy establishment wants.

Military intervention around the world costs Americans substantial blood and treasure and benefits them little.

In a world with terrorism and nuclear weapons, it is better to keep military conflicts limited.

David Boaz is executive vice president of the Cato Institute and author of “The Libertarian Mind.” Send comments to [email protected].