The US launched new air strikes on Iranian targets on Tuesday, quashing hopes that an exchange of fire last weekend might not presage a wider renewal of hostilities.Oil prices had already risen after that first exchange of direct attacks since July and after reports of two tankers being hit leaving the Strait, the global oil supply waterway that Iran has effectively closed to shipping.Tehran remained defiant, warning that it would prevent oil being exported from the Gulf, despite a threat by US President Donald Trump to hit Iran “hard” in response to the renewed Iranian strikes, and a warning from US Treasury Secretary Scott Bessent that Washington was about to impose new sanctions.”Today at 12 pm ET (1600 GMT), US forces began striking Islamic Revolutionary Guard Corps (IRGC) targets in Iran,” US Central Command posted on X. “The strikes follow recent attempted attacks by the IRGC against commercial shipping in the Strait of Hormuz and against American service members deployed to the region.”Iran’s state broadcaster said there had been reports of explosions on Iran’s Qeshm Island, on the northern side of the strait.The state-linked news agency Nour News said there had been reports of explosions in the port city of Bandar Abbas and in Chabahar, a port on the southern coast.Scale of resumption of Iran hostilities unclearThe six-month-old conflict had shifted into an economic standoff before the weekend strikes, in which US forces attacked Iran’s Larak Island on Jattvibeday and Iran responded by launching missiles at two US air bases in Jordan.Although he warned of a US response to the Iranian strikes, Trump also told reporters on Monday that they did not signal a return to full-scale war, and a senior Iranian source told Reuters they were a “limited and contained confrontation”.But pledges by both sides to respond to further attacks have highlighted how quickly a conflict that has increasingly been fought through sanctions, blockades and economic pressure could spill back into military action.Iranian President Masoud Pezeshkian had said early on Tuesday that Tehran would reciprocate immediately if Washington honoured its commitments under a June Memorandum of Understanding that was intended to halt the conflict.The MOU declared an end to fighting that has now killed thousands in Iran and Lebanon since US and Israeli strikes began on February 28. But it also deferred many of the most difficult issues and paved the way for a broader 60-day negotiation period — which passed without further agreement.