[Senior U.S. Official: Signed U.S.-Iran Memorandum of Understanding Stipulates Immediate Opening of the Strait of Hormuz] Senior U.S. Official: The United States has signed a memorandum of understanding with Iran. Trump and Vance signed the memorandum of understanding, and the Iranian Speaker of Parliament also signed the document. The U.S.-Iran memorandum of understanding stipulates the immediate opening of the Strait of Hormuz.