President Donald Trump on Tuesday escalated a war of words with German Chancellor Friedrich Merz, accusing him of being soft on Iran’s nuclear ambitions even as the German leader has explicitly argued that Tehran must never obtain a nuclear weapon.

Trump, posting on Truth Social, claimed Merz “thinks it’s OK for Iran to have a Nuclear Weapon” and “doesn’t know what he’s talking about,” a charge that added to already strained relations between Washington and key NATO allies.

Merz had said a day earlier that Iran’s leadership was “humiliating” the United States in ongoing efforts to negotiate an end to the war, pointing to episodes in which U.S. officials traveled for talks only to leave without concrete progress.

He also questioned the broader U.S. strategy, saying he did not see a clear exit plan from the conflict, remarks that amounted to one of the sharpest public criticisms yet from a European leader aligned with the United States.

The exchange comes as Trump has been clashing with NATO partners over his administration’s aggressive posture in the region, particularly a U.S.-led blockade around the Strait of Hormuz aimed at restricting Iran’s oil exports and military resupply.

Several European governments, including Germany, have resisted direct involvement in the blockade, wary of escalation risks and the legal and economic implications of interdicting shipping in one of the world’s most critical transit corridors.

Those disagreements have widened an already visible rift inside the alliance, with European officials privately and publicly pressing for a diplomatic offramp while the Trump administration has doubled down on economic and military pressure.

Merz’s comments underscored that divide, suggesting some allies had doubts not only about the effectiveness of U.S. tactics but also about whether Washington has articulated a viable path to ending the conflict.

Trump, for his part, has framed allied hesitation as a failure to confront Iran decisively, arguing that stronger collective action — including support for the Hormuz blockade — is necessary to force Tehran into concessions on both its regional activities and nuclear program.