In July, officials from around the world will arrive in Washington, DC, for the 75th^–anniversary summit of the North Atlantic Treaty Organization. Amid the celebrations, it is worth reflecting on how NATO began and why it matters today.

In the aftermath of World War II, 12 nations formed the Western alliance to deter the Soviet Union, stabilize Europe, and promote regional integration. The effort was an incredible success. The Soviet Union is no more. There has been no great-power war in Europe since NATO’s foundation. And the trans-Atlantic [alliance] is more interconnected than at any point in its history.

NATO has achieved more than the goals of its founders. It has expanded its ranks to include 32 member states and some 40 international partners. It has kept the peace in the Balkans and Kosovo. It participated in the American-led Global War on Terror. It toppled the government of Colonel Moammar Qaddafi in Libya. Since 2022, NATO has helped Ukraine resist invasion by Vladimir Putin’s Russia. In other words, this 75-year-old is far from obsolete. Quite the opposite: NATO is more essential than ever.

The alliance is important because it remains the sturdiest international organization of the postwar era.

After victory over the Axis powers in 1945, America and her allies were determined to prevent a third world war. NATO bound its members together with the collective security provision contained in its charter. The backstop of “Article Five” of the Atlantic Treaty was America’s nuclear arsenal. This hard power guarantee did not simply coincide with the economic and political revival of Western Europe. It was a cause of that revival.

The same cannot be said of NATO’s fellow postwar institutions.

The U.N. is little more than a stage for a grotesque farce. Former national security adviser John Bolton once said that if you lopped 10 floors off the U.N. building in New York, “it wouldn’t make a bit of difference.”  The U.N. could disappear tomorrow and only the bad guys would notice.

Other postwar initiatives are not as malign as the U.N. They are merely irrelevant. The Marshall Plan was such a success that it was no longer necessary. President Lyndon Johnson’s “guns-and-butter” budgets of war in Vietnam and Great Society at home brought the Bretton Woods monetary system to the brink of collapse. President Nixon put it out of its misery.

The World Trade Organization is dysfunctional, torn between the warring economic blocs of China and America. The World Bank and IMF putter along— well meaning, politically correct, and perfectly ineffectual.

NATO endures because at the heart of the alliance is a sense of purpose and shared values. Membership in NATO is voluntary, stringent, and exclusive. No Communists allowed.

NATO has always understood itself to be a bulwark of freedom and self-government. This self-conception has shielded it from the insidious forces that have corrupted the likes of the U.N.

Twenty years ago, several foreign policy wonks proposed the formation of a “League of Democracies.” They were late to the game. One already exists. NATO’s durability, effectiveness, and appeal rest on its principles and its clearly defined mission.

But NATO is not without problems. Abandoning Ukraine would be a terrible blow to NATO’s credibility. The Eastern European member states would begin to hedge against American isolationism. The French and the Germans would begin to explore alternative security structures.

Russia would probe for weaknesses. And the Eurasian axis of autocrats—Putin, Ayatollah Ali Khamenei, Kim Jong Un, and Xi Jinping—would be emboldened. As NATO Secretary General Jens Stoltenberg put it in a recent speech to the Heritage Foundation: “It is Ukraine today. Taiwan could be tomorrow.”

The good news is that NATO can be strengthened. All it would take is some guts on the part of Western European politicians to increase defense spending, and a renewed commitment of American resources and willpower to international security.

The investment in time and resources necessary to maintain the oldest military alliance in human history is small. But the cost of watching this last pillar of the postwar order crumble into dust would be incalculable.