US Secretary of State Mike Pompeo vowed on Sunday that the US will guarantee free passage through the vital Strait of Hormuz, as he accused Iran of recent attacks on oil tankers and the downing of a US drone. Pompeo confirmed in an interview with CBS that a US MQ-9 “Reaper” drone was shot down on June 6 with a missile fired from Yemen “that we assess had Iranian assistance”. Pompeo would not be drawn on what options the US is considering to protect shipping – or to punish Iran – in the wake of Thursday’s attacks on two tankers in the Gulf of Oman, but reiterated that US President Donald Trump is not seeking war with Iran. “What you should assume is we are going to guarantee freedom of navigation throughout the strait,” he said in an interview on Fox News Sunday . Iran has denied the US charges as “baseless” and said they were made without “a shred of factual or circumstantial evidence.” A third of the world’s seaborne oil supply passes through the Strait of Hormuz, a narrow channel bordered to the north by Iran that links the Gulf with the Gulf of Oman. “This is an international challenge, important to the entire globe. The United States is going to make sure that we take all the actions necessary, diplomatic and otherwise, that achieve that outcome,” Pompeo said. The rising tensions have raised fears of an outbreak of hostilities in the tinderbox region. Crew saw ‘flying objects’ before Japanese ship attacked in Gulf “We don’t want a war. We’ve done what we can to deter this,” Pompeo said. “The Iranians should understand very clearly that we will continue to take actions that deter Iran from engaging in this … kind of behaviour.” The secretary would not lay out US evidence for Iran’s involvement in the Gulf of Oman explosions, but insisted: “It’s unmistakable what happened here. “These were attacks by the Islamic Republic of Iran on commercial shipping, on the freedom of navigation, with the clear intent to deny transit through the strait.” The Pentagon had previously released a video showing what it said was an Iranian boat that pulled up alongside one of the stricken tankers and removed a limpet mine attached to its hull. Some allies, sceptical of US intentions, have said they wanted to see more evidence before reaching a conclusion. “I will concede that there are countries that wish this would just go away,” Pompeo said. He expressed confidence that “as we continue to develop the fact pattern, countries around the world will not only accept the basic facts, which I think are indisputable, but will come to understand that this is an important mission for the world”. Sanctions drive Iranian students away from US towards Asia Adam Schiff, head of the House Intelligence Committee and a leading Democratic critic of the administration, said the evidence of Iranian involvement “is very strong and compelling”. “And in fact, I think this was a Class-A screw-up by Iran to insert a mine on the ship,” he said on CBS’s Face the Nation . “It didn’t detonate, they had to go back and retrieve it. I can imagine there are some Iranian heads rolling from that botched operation,” he said. The administration’s struggle to persuade its allies, however, “shows just how isolated the United States has become”, he added.