Donald Trump has threatened to pull troops out of Germany after Friedrick Merz said the US was "humilated" by Iran.
As of December 2025, the US currently has more than 36,000 troops assigned to bases across Germany - the largest presence in all of Europe.
But now the US President announced he was "studying and reviewing" the possibility to reducing troops in the European country.
He said a decision would be made "over the next short period of time".
On Monday, the German Chancellor told students that "the Americans clearly have no strategy" and could not identify a "strategic exit" amid the Iran war.
He added: "The Iranians are obviously very skilled at negotiating, or rather, very skilful at not negotiating, letting the Americans travel to Islamabad and then leave again without any result.
"An entire nation is being humiliated by the Iranian leadership, especially by these so-called Revolutionary Guards. And so I hope that this ends as quickly as possible.
"It’s not just about getting in; you also have to get out. We saw that all too painfully in Afghanistan, for 20 years. We saw it in Iraq."
Donald Trump has threatened to pull troops out of Germany
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His words have appeared to rattle the US President, who claimed Mr Merz "doesn't know what he's talking about".
In a furious Truth Social post, he said: "No wonder Germany is doing so poorly, both Economically, and otherwise!"
Germany is, overall, the largest economy in Europe.
But Mr Merz refused to be shaken, assuring reporters later in the week that the "personal relationship between me and the American President remains just as good as before".
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German Chancellor Friedrich Merz met with army officials today
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He added he "simply had doubts from the start about what was begun with the war in Iran".
However, he is yet to reply to Mr Trump's consideration to reduce America's military presence in the European nation.
Mr Merz's criticism over American's offensive action against Tehran is likely to fuel further criticism of Europe from the President.
Earlier this month, after Sir Keir Starmer initially refused to allow US bombers to launch strikes from British bases, Mr Trump fired off a number of personal jibes.
During a press conference, he said the PM was "no Churchill" - the wartime hero whom Mr Trump holds dear.
It also came after the President branded the Chagos surrender bill an "act of great stupidity".
The President even hit out at Italian Prime Minister and long-time ally Giorgia Meloni after she defended the Pope earlier this month.
The US President said Ms Meloni was "very different to what he thought" and admitted he was "shocked" after she criticised his online rants branding Pope Leo "weak on crime" and "terrible for foreign policy".