President Trump also said the United States would charge a 20 percent fee on goods passing through the Strait of Hormuz.

President Trump also said the United States would charge a 20 percent fee on goods passing through the Strait of Hormuz. The United States and Iran on Monday appeared to be reverting to the conflict that raged before their cease-fire, as a new round of attacks gave way to President Trump’s statement that he would restart the naval blockade of Iran, and Iranian vows to avenge the killing of the country’s supreme leader. Mr. Trump has formally notified Congress that fighting with Iran resumed, a recognition that the truce is breaking down and one that stokes a struggle over vital war powers. Congress has directed the president to either end the war or seek approval to continue it, but Mr. Trump insists he has the sole authority to make that call. The notification letter, dated Friday, was obtained by The New York Times on Monday. The president said the United States would take control of the disputed Strait of Hormuz, charging a 20 percent fee on all goods passing through it, while blockading Iranian ports. He had lifted the blockade last month after the two countries reached a truce, which has been threatened by repeated strikes by both sides. Mr. Trump told Fox News that the United States would charge other countries for keeping the strait safe. “We are going to guard it and we’re going to get paid for guarding it,” he said. The suggestion, which would amount to an expansion of the military conflict, echoed previous threats that had not come to pass. Hours earlier, Ali Bagheri Kani, the deputy secretary of the Supreme National Security Council, was among the Iranian officials calling for revenge against the United States over the killing of the Supreme Leader Ayatollah Ali Khamenei, describing it as “the right of the Iranian nation,” according to the state broadcaster. Iran’s military said early Monday that it had launched another barrage of strikes aimed at American military assets in Jordan, Bahrain, Kuwait and Oman. Hours earlier, U.S. forces said they had launched more strikes aimed at stymying Iran’s ability to attack commercial ships in the Strait of Hormuz. The latest exchange caps a nearly weeklong flare-up of hostilities as the United States and Iran tussle over control of the strait, through which a fifth of the world’s oil and liquefied natural gas passed before the war.