There are between 34,000 and 35,000 US soldiers permanently stationed in Germany, according to the Pentagon, although rotation of units mean the overall number can temporarily top 50,000.
US President Donald Trump on Monday said he is cutting the number of US troops in Germany by half because Berlin is "delinquent" in its contributions to NATO and treats the US "badly" on trade.
Trump told reporters there are 52,000 US soldiers stationed in Germany.
"It's a tremendous cost to the United States," he said. "So we're removing a number down to, we're putting the number down to 25,000 soldiers."
US troops have been stationed in the geopolitically vital country since the end of World War II, forming the bulk of the NATO alliance's conventional defence against the Soviet Union during the Cold War.
Insufficient NATO payments
The resurgence of Russia's military ambitions under President Vladimir Putin have given the US presence a new importance in the last two decades, with central and eastern European states leading the way in pressuring for stronger US-led defences.
However, Trump said he was reacting to ally Germany's insufficient payments to NATO.
"Germany's delinquent, they've been delinquent for years and they owe NATO billions of dollars, and they have to pay it. So we're protecting Germany and they're delinquent. That doesn't make sense," he said.
Trump has repeatedly accused European NATO members of freeloading on the US by falling short of their commitment to spend at least two percent of GDP on defence.
Senior German politicians expressed concern last week about reports the US was planning to cap troop numbers at around 25,000, which appeared to catch Berlin by surprise.
The plan raised fresh questions about Trump's commitment to longstanding cooperation agreements with European allies, with some observers fearing the move could undermine NATO security.
Trump said Germany as the economic powerhouse of the European Union was also to blame because "they treat us very badly on trade."
"We're negotiating with them on that but right now I'm not satisfied with the deal they want to make. They've cost the United States hundreds of billions of dollars over the years on trade, so we get hurt on trade and we get hurt on NATO."
He complained that Germany was profiting from the US troop presence.
"Those are well-paid soldiers. They live in Germany, they spend vast amounts of money in Germany. Everywhere around those bases is very prosperous for Germany. So Germany takes."