Iran’s state media said on Saturday that US forces had attacked an Iranian oil tanker off the coast of the strategically important Kharg Island, days after the two sides engaged in the heaviest fighting in weeks. The United States has not confirmed the Iranian reports. A U.S. military spokesman did not immediately respond to a request for comment. Kharg Island in the Persian Gulf is the main hub for Iran’s oil exports, which have been squeezed for weeks by a US naval blockade of Iranian ports. Iranian media, including the state broadcaster, said at least one US missile had hit the tanker and published images of a ship emitting plumes of black smoke. Tasnim, a semi-official news outlet affiliated with Iran’s Islamic Revolutionary Guard Corps, reported that the attack took place on Saturday morning and that the tanker’s crew had survived and were being evacuated. The reports come as the fate of the Strait of Hormuz, a waterway on Iran’s southern coast, has become central to the conflict between Iran and the United States. The strait previously served as a major shipping route for oil and other key commodities, but Iran has sought to control it since the country was attacked by the United States and Israel earlier this year. The US Navy has been helping ships navigate a southern route through the strait, near the coast of Oman, provoking retaliation from Iran. On Monday, two oil tankers were attacked within minutes of each other as they attempted to pass. There was about a month of relative calm in the conflict between Iran and the United States until late August, when the two sides exchanged fire. This week, US forces carried out a barrage of strikes in retaliation for Iranian attacks on US ships and forces in the region. One of the attacks hit a wedding in southern Iran, killing five people and wounding dozens, according to Iranian officials. President Trump issued a new threat to Iran on Friday, saying the United States could attack Pickaxe Mountain, a suspected Iranian nuclear site, “very soon.”