Iran will shift to a "fully offensive" military posture because efforts to negotiate a permanent end to its war with the United States have stalled, as the US ruled out extending a temporary ceasefire agreement.Progress towards peace talks and a resumption of oil tanker traffic through the strategic Strait of Hormuz has ground to a halt, with no sign that the warring parties are moving towards ending the conflict that the US and Israel launched with attacks on Iran on 28 February."Iranian entities must be prepared to escalate tensions in the Strait of Hormuz and wider region, as Iran will be ready to make decisions and take action on difficult decisions," a senior Iranian official told Reuters news agency The official added that Iran would conduct a "timely and precise" military attack to break the US naval blockade if diplomacy failed.Monday marked the day Iran and the US were expected to reach a final peace agreement under a memorandum of understanding signed in June aimed at ending the war.Signed on 17 June, the MoU set a 60-day timeframe for the US and Iran to reach a broader deal on Iran's nuclear program and US sanctions.The agreement, which declared the "immediate and permanent termination of military operations on all fronts", quickly unravelled over a dispute about control of the Strait of Hormuz, the narrow waterway through which a fifth of global oil and liquefied natural gas flowed before the war.Asked by reporters on Monday if the US was seeking to extend June's interim agreement, US President Donald Trump said no.Iran said point 5 of the MoU gave it the right to manage the strait, which it shares with Oman, while the US rejected that interpretation