Trump said that Washington was considering redeploying some of the tens of thousands of its troops stationed in Germany amid a row with Merz over the war in Iran.

Speaking during a visit to Morocco, German Foreign Minister Johann Wadephul said: "We are prepared for that, we are discussing it closely and in a spirit of trust in all NATO bodies, and we are expecting decisions from the Americans."

Any such decisions would "be discussed with us and with others, as is proper among allies", he added.

Merz earlier said that Germany's approach to the war in the Middle East "remains oriented toward a united NATO and a reliable transatlantic partnership".

Berlin was "in close and trusting contact with our partners, including and especially in Washington", he said, without directly mentioning the Trump threat.

"We are doing this in our shared transatlantic interest. We are doing it with mutual respect and a fair sharing of burdens," he added.

Merz became a target of Trump's ire after saying earlier this week that Iran was "humiliating" Washington at the negotiating table.

Trump said on Tuesday that Merz "thinks it's OK for Iran to have a Nuclear Weapon. He doesn't know what he's talking about!"

Then on Wednesday, in a post on his Truth Social platform, Trump said he was considering reducing the number of troops in Germany.

And on Thursday, Trump told Merz to focus on ending the Ukraine war instead of "interfering" on Iran.

"The Chancellor of Germany should spend more time on ending the war with Russia/Ukraine (Where he has been totally ineffective!), and fixing his broken Country, especially Immigration and Energy," Trump said on his Truth Social network.

He added that Merz should spend "less time on interfering with those that are getting rid of the Iran Nuclear threat, thereby making the World, including Germany, a safer place!"

While saying he was "relaxed" about the idea of fewer US troops in Germany, Wadephul, the foreign minister, said that large American bases in Germany are "not up for discussion at all".

He said for example that the Ramstein Air Base had "an irreplaceable function for the United States and for us alike".