President Trump said Wednesday he is considering reducing the number of U.S. forces in Germany, amid a spat with Germany's chancellor and the NATO alliance over Iran. 

"The United States is studying and reviewing the possible reduction of Troops in Germany, with a determination to be made over the next short period of time," he wrote on Truth Social. 

The U.S. military has a massive presence in Germany that dates back to the aftermath of World War II and the Cold War. More than 36,000 active duty troops were assigned to bases throughout Germany as of last December, along with nearly 1,500 reservists and 11,500 civilians, according to Defense Department figures. Japan is the only foreign country with a larger presence of U.S. troops. 

Germany is also home to the headquarters of U.S. European Command and Africa Command, and its Ramstein Air Base is a key hub for U.S. operations.

The president has grown increasingly frustrated with the U.S.'s allies in Europe, which have sought to keep their distance from the U.S.-Iran war. He has threatened to leave NATO, calling the alliance a "paper tiger" for not entering the war. A 2023 law prevents the president from withdrawing the U.S. from NATO without approval from Congress.

Meanwhile, Europe is grappling with higher energy prices as the Iran conflict severely constrains oil exports from the Middle East.

German Chancellor Friedrich Merz appeared to draw Mr. Trump's ire after he criticized the U.S.'s handling of the war earlier this week, saying "the Americans clearly have no strategy" on Iran and suggesting the U.S. is being "humiliated" by Iranian negotiators.

On Tuesday, Mr. Trump wrote on social media that Merz "thinks it's OK for Iran to have a Nuclear Weapon" and "doesn't know what he's talking about." 

"No wonder Germany is doing so poorly, both Economically, and otherwise!" the president said.

Hours before Mr. Trump floated troop reductions, Merz told reporters he still is on good terms with the U.S. president, despite their well-publicized disagreements over Iran strategy.

Mr. Trump's skepticism of NATO predates the Iran war. He has long accused member states of not spending enough on defense and of being too reliant on the U.S. for security. 

In 2020, the final year of his first term, Mr. Trump announced plans to pull around 12,000 U.S. forces from Germany, after accusing the European country of being "delinquent" in military spending. The plan drew bipartisan pushback and was reversed by former President Joe Biden.

In a smaller move last fall, U.S. officials told CBS News that around 700 troops who were deployed in Germany, Romania and Poland would return home. U.S. Army Europe and Africa said it was part of a "deliberate process to ensure a balanced U.S. military force posture," and was "not an American withdrawal from Europe or a signal of lessened commitment to NATO."