By Andreas Rinke and Miranda Murray

BERLIN, March 24 (Reuters) - The Iran war is a "disastrous mistake" that breaches international law, Germany's president said on Tuesday in an unusually blunt ‌rebuke of U.S. President Donald Trump's foreign policy, which he said marked a rupture for ‌German ties with its biggest post-war ally.

In a scathing verbal attack, Frank-Walter Steinmeier, whose largely ceremonial role allows him to ​speak more freely than politicians, took a far more critical line than Chancellor Friedrich Merz, who has skirted questions on the war's legality.

"Our foreign policy does not become more convincing just because we do not call a breach of international law a breach of international law," Steinmeier, a former foreign minister from the ‌centre-left Social Democratic Party, said in ⁠a speech at the foreign ministry.

"We must address this with regard to the war in Iran. For, in my view, this war is contrary to international ⁠law," he said, adding he had little doubt that the justification of the imminent nature of an attack on U.S. targets did not hold water.

Calling the war unnecessary and a "politically disastrous mistake", Steinmeier said Trump's second ​term ​marked a rupture in German foreign relations as profound ​as Russia's invasion of Ukraine.

"Just as I ‌believe there will be no going back in relations with Russia to before February 24, 2022, so too do I believe there will be no going back in transatlantic relations to before January 20, 2025," said Steinmeier.

REDUCING DEPENDENCY

Germany had to apply lessons it learned in extricating itself from "excessive dependencies" on Russia and apply them to the U.S., particularly in defence and technology, which translate to power, he ‌said.

Germany has stressed the importance of creating alternatives to ​U.S.-dominated technology as concerns grow over U.S. access.

China returned to ​being Germany's top trading partner in the ​first eight months of 2025, overtaking the U.S. as higher tariffs weighed on ‌German exports. Trade between the U.S. and Germany ​amounted to more than ​163 billion euros ($190 billion) over that period.

The recent spat between the Pentagon and Anthropic over safety guardrails surrounding the latter's artificial intelligence could be a wake-up call, or even an opportunity, ​for Europe, said Steinmeier.

"Europe as ‌a technology hub has talent, markets, opportunities and, importantly, ethical standards. We should build on ​these," he said.

(Reporting by Andreas Rinke and Miranda MurrayWriting by Miranda Murray and Madeline ​Chambers Editing by Ludwig Burger and Aidan Lewis)