WASHINGTON (AP) — Iran launched multiple ballistic missiles at American forces in the Middle East on Tuesday, shattering a brief pause in fighting as mediators tried to get both sides back to negotiations and toward a ceasefire, the U.S. military said.

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All Iranian missiles were successfully intercepted, U.S. Central Command said in a statement, adding that U.S. forces "remain vigilant and at a high state of readiness."

The U.S. and Iran had experienced a brief period of calm, during which neither announced attacks for days following weeks of escalation over the Strait of Hormuz. The Persian Gulf waterway is a narrow chokepoint through which 20% of the world's oil normally flows.

Iran effectively closed the strait when the war began by firing at freighters and tankers off its coast or threatening, too. Following the signing of an interim ceasefire deal in June, a battle for control over the strait has erupted. Iran demanded that ships use a route near its coastline and said it can potentially charge fees. Ships were increasingly navigating a southern route along the coast of Oman under a U.S. overwatch operation when Iran attacked some vessels.