President Donald Trump on Sunday warned Iran "there won't be anything left of them" if Tehran does not quickly agree to a peace deal with the United States.
Washington, locked in conflict with Tehran since US and Israeli forces launched major strikes on the Islamic republic beginning February 28, has struggled to break an impasse and make any progress toward ending a war that has shaken the Middle East and sent energy prices climbing.
"For Iran, the Clock is Ticking, and they better get moving, FAST, or there won't be anything left of them," Trump wrote on his Truth Social platform. "TIME IS OF THE ESSENCE!"
The war has led to an effective blockade of the critical Strait of Hormuz, through which some 20 percent of global oil exports pass in peacetime, and has drawn neighbors Israel and Lebanon into a deadly side conflict.
Iran's clerical state, Hezbollah's patron, has demanded a lasting ceasefire in Lebanon before any broader peace agreement with Trump, who has been frustrated by Tehran's refusal to an accord on his terms.
An Israeli military official said Sunday that Hezbollah had fired around 200 projectiles at Israel and its troops over the weekend, despite Israel and Lebanon agreeing to extend a ceasefire.
Washington and Tehran agreed to a truce on April 8, but peace negotiations have stalled and sporadic attacks have continued.
On Sunday, Iranian media said the United States had failed to make any concrete concessions in its latest response to Iran's proposed agenda for negotiations to end the war.
The Fars news agency said Washington had presented a five-point list which included a demand for Iran to keep only one nuclear site in operation and transfer its stockpile of highly enriched uranium to the United States.