The announcement came as talks set to take place between U.S. and Iranian delegations in Pakistan were postponed amid uncertainty about the broad strokes of a deal.

The blockade could derail a tenuous ceasefire after just five days. Vice President JD Vance said the U.S. remains open to diplomacy if Iran takes “our final and best offer.”

Vice President JD Vance was leading the highest level of face-to-face engagement between leaders of the United States and Iran in decades.

Iran accused the U.S. and Israel of violating the truce and threatened to withdraw from negotiations. Israeli attacks in Lebanon were a major point of dispute.

The vice president traveled to Budapest as Trump’s deadline for an Iran deal loomed Tuesday, backing the administration’s closest ideological ally in Europe.