The Pentagon announced on Friday that it would pull 5,000 troops from Germany, a U.S. ally that has found itself at odds with President Trump.

That would reduce one of the world’s largest overseas deployments of American troops, but tens of thousands would remain. Germany hosts more than 36,000 active-duty personnel, according to the U.S. Defense Manpower Data Center — more than any foreign country but Japan. The Pentagon said the withdrawal would return the U.S. troop presence in Europe to the level it was at before Russia invaded Ukraine in 2022.

Roughly half of the American military personnel stationed in Europe are in Germany, which is home to five of the nine U.S. Army garrisons on the continent. That troop presence, rooted in a longstanding alliance, has created a huge American military ecosystem.

Why are there so many U.S. troops in Germany?

The American military has been stationed in Germany since the Allies defeated the Nazis in World War II. Its presence at Wiesbaden, for instance, began when U.S. troops occupied an air base abandoned by the Luftwaffe in 1945. Today, Garrison Wiesbaden hosts U.S. Army Europe and Africa headquarters.

During the Cold War, West Germany was effectively the front line against what was then the Soviet Union. The American troop presence there grew as part of its military buildup during the decades-long standoff with Soviet Russia.

It is also crucial to NATO, the military alliance that was originally formed to counter the perceived threat of Soviet expansion. Ramstein Air Base, for instance, one of the best-known overseas U.S. bases, hosts a NATO installation, with forces from Germany, Britain, Canada, France and 21 other members of the alliance.

What do the troops do?

American military personnel in Germany carry out a broad range of activity, from operations to logistics and more. As of December, there were 22,727 active-duty Army personnel in Germany, and 12,628 Air Force personnel. The Marines, the Navy, the Coast Guard and Space Force also have personnel there.

U.S. European Command, which has overseen American military activity across Europe since the end of World War II, is based in Germany. From its headquarters in Stuttgart, the command is responsible for coordinating the flow of weapons to Ukraine, among many other tasks.

American personnel stationed in Germany play roles well beyond Europe. U.S. Africa Command, in fact, is also headquartered in Stuttgart, in southwestern Germany. Landstuhl Medical Center, the largest American hospital outside the continental United States, treats active-duty personnel from Europe, the Middle East and Africa.

A local employer

Military facilities create ecosystems where they are built, serving local residents as well as American military families. U.S. Army garrisons host schools, training facilities, fire departments and hospitals.

The garrisons in Germany are mostly in rural areas, and American communities have sprung up around them. For decades, tens of thousands of Americans have lived in Kaiserslautern, a city in Rhineland-Palatinate state, near the Ramstein base and other Air Force and Army installations.

The Kaiserslautern Industrial Center is in that region, producing ammunition, maintaining equipment and driving the military supply chain. The American military is one of the area’s largest employers.