For most Americans, U.N. peacekeeping is something the rest of the world does. Indeed, the U.N. monitoring mission that is currently in Syria to enforce a floundering ceasefire features blue berets from 35 countries — including Burkina Faso, China, Germany, Kyrgyzstan, Morocco, Russia, and Yemen — but none from the United States. The absence of American personnel partly reflects Syria’s antipathy toward the United States, which has called for Syrian President Bashar al-Assad to step down. But it also reflects the fact that U.S. blue helmets have become an increasingly extinct species.

It wasn’t always that way, however.

In 1948, when the United Nations set up its first peacekeeping mission in the Middle East to monitor a truce between Israel and five Arab countries, it placed 21 American observers under the command of a Swede, Col. Count Thord Bonde. As the United Nations branched out into Africa and South Asia, the U.S. Air Force provided the airlift capacity, ferrying thousands of international peacekeepers to duty from Congo to the Sinai.

The United States still contributes generously to U.N. peacekeeping operations, paying for about 27 percent of the organization’s $8 billion budget, and European governments pay much of the remainder. But Western nations have withdrawn from the most ambitious operations, particularly in Africa. Where they remain, they serve alongside U.N. forces, as in the case of the French forces stationed in Ivory Coast.

A tour of the U.N. photo archives shows just how the complexion and nationality of U.N. blue helmets has changed over time.