Iran’s Supreme Leader’s representative Mojtaba Khamenei issues a written warning to the United States, saying repeated U.S. breaches of a memorandum of understanding have shown that President Donald Trump’s signature is “worthless” and “devoid of credibility.” In statements reported by multiple outlets, Khamenei characterizes the situation as proof that the U.S. commitment lacks credibility and adds that continued attacks could bring “unforgettable lessons” for the U.S. Army. The warnings come as Washington and Tehran exchange strikes following the collapse of a ceasefire agreement reached after an interim arrangement earlier in the month. Several reports describe renewed military actions targeting infrastructure and military sites, and note rising fears of a wider conflict. The messaging frames U.S. behavior as “bullying,” while the dispute centers on whether the ceasefire terms and related commitments are being followed. Across the accounts, the central points are Khamenei’s rejection of the memorandum’s validity, his threat of retaliation if attacks persist, and the ongoing exchange of strikes amid the breakdown of de-escalation efforts.