WASHINGTON \u2014 U.S. forces struck Iranian rocket launchers on the Strait of Hormuz in their first military action in a month on Sunday, breaking a lull in fighting during an intermittent war that has lasted more than six months. Iran swiftly vowed to retaliate for what it called a deadly attack.Forces with the Revolutionary Guard Corps were observed preparing to launch rockets with sea mines into the strait, according to Tim Hawkins, a spokesperson for the U.S. Central Command. The U.S. military last week completed clearing sea mines from the strait's international shipping routes.Semiofficial news outlets in Iran reported sounds of explosions near Larak island on the strait. The Guard in a statement carried by Iran's state broadcaster noted "the martyrdom and injury of several of our fighters and compatriots."A return to open conflict would be dangerous for the region, where Iran has targeted U.S. military bases and infrastructure in Gulf countries since the war began on Feb. 28.The last time the U.S. military confirmed targeting Iran was on July 29, when it announced a "heavy wave of strikes" on dozens of Revolutionary Guard targets including coastal surveillance and defense sites. On Aug. 1, President Donald Trump said he would order the military to hold off on new strikes at the urging of Gulf allies Qatar, Saudi Arabia and the United Arab Emirates.The attack comes just days after the Trump administration said it would turn its focus to increasing economic pressure \u2014 rather than military action \u2014 to try to end its war with Iran. The shifting strategy centers on threats to punish any country or entity that continues to conduct business with Tehran.Sunday's attack was a "fatal mistake by the Trump regime during the economic war," and the enemy will pay the consequences militarily and economically, a Guard spokesperson, Gen. Hossein Mohebi, said in a statement carried by Iranian media.The U.S. turn to using sanctions came as the administration weighs diminished munitions stockpiles after months of war, sparking concerns that the prolonged conflict could undermine U.S. military readiness in other parts of the globe.As the conflict grinds on, Trump's talk of finding a quick end to the war also appears to be fading. He stressed last week that he's "not in a hurry" to get Iran back to the negotiating table, and he continues making the case that the Islamic Republic's leadership is on the ropes.Appointments to Iran's senio