Washington/Tehran, March 27 -- President Donald Trump threatened Iran with intensified military action, seeking to pressure the country to ramp up negotiations on an end to the war even amid uncertainty over the status of those discussions. "They better get serious soon, before it is too late, because once that happens, there is NO TURNING BACK, and it won't be pretty!" Trump posted on social media Thursday. The president's comments come as Washington has been insisting that peace talks are ongoing, despite Tehran publicly rejecting overtures from the US and instead issuing conditions of its own. "They are 'begging' us to make a deal, which they should be doing since they have been militarily obliterated, with zero chance of a comeback, and yet they publicly state that they are only 'looking at our proposal.' WRONG!!!," the president said, echoing comments he made at a fundraiser on Wednesday. The US and Israel began a bombing campaign in Iran almost a month ago, leading Tehran to effectively close the Strait of Hormuz, snarling the flow of oil and roiling markets. Trump on Monday said he was delaying for five days a threat to begin targeting Iran's power infrastructure to allow talks for a deal. "The United States has been engaged over the last three days in productive conversations," White House Press Secretary Karoline Leavitt told reporters earlier in the day. "You're beginning to see the regime look for an exit ramp." Their comments ran counter to Iran's earlier statements through state-run media publicly rejecting Trump's push for talks. Tehran is also seeking its own guarantees, including that the US and Israel won't resume their attacks, reparations for war damages and recognition of its authority over the Strait of Hormuz, state-owned Press TV said. As the war grinds on, each side has kept up attacks even amid renewed efforts to jawbone the other into a resolution. And so far, Tehran is showing little sign of backing down despite daily bombardment. The Israel Defense Forces completed a wave of strikes in Isfahan, in the center of the country, in what it described as an attack aimed at infrastructure across different areas of Iran. Several housing units were destroyed and multiple homes left seriously damaged when Isfahan came under attack early Thursday, according to the semi-official Fars news agency, which reported no fatalities so far. The UAE said its air defenses were responding to Iranian missile and drone threats, while Bahrain said an Iranian attack caused a fire at a facility in Muharraq. Early on Thursday, Iran's armed forces said they carried out missile strikes targeting American forces and separatist groups backed by the US-Israeli alliance in the northern Iraqi city of Erbil, describing the attacks as part of their latest operations. Iran is also looking to formalize a transit fee for the Strait of Hormuz, with lawmakers working on a draft bill to impose a toll in exchange for providing security to ships passing via the key waterway, according to Fars. Tehran has already begun charging a limited number of commercial vessels for transit, with payments of as much as $2 million per voyage being sought on an ad hoc basis, according to people familiar with the matter. Since the war started nearly four weeks ago, Iran has effectively shuttered the conduit for about a fifth of the world's oil and liquefied natural gas, triggering a global supply shock. Now days away from Trump's Friday deadline for Iran to negotiate a deal to end the war, there are lingering questions over the status of negotiations and the likelihood for a deal. The US compiled a 15-point peace proposal that Pakistan delivered to the Islamic Republic, according to people familiar with the matter, highlighting the urgency within Trump's administration to resolve a conflict it started alongside Israel almost a month ago. Leavitt on Wednesday said there were "elements of truth" to the reported US proposal, but cautioned against speculating on anonymously provided plans. Vice President JD Vance may travel to Pakistan for Iran talks this weekend, CNN reported. Asked for comment on that report, Leavitt said "this is a fluid situation, and speculation about meetings should not be deemed as final until they are formally announced by the White House." The conflict has led to surging fuel and fertilizer prices, with commercial tankers avoiding crossing the Strait of Hormuz and Iranian attacks damaging energy infrastructure. It has also sparked fears of an inflation crisis and worldwide food shortages. Brent oil is on pace for the biggest monthly gain since 1990 as the US and Iran offer conflicting comments on efforts to end the war. The global crude benchmark rose toward $104 a barrel after losing more than 2% on Wednesday, while West Texas Intermediate was near $92. The risks of further escalation are still substantial. The White House has asserted that Trump is keeping all options open for expanded military action. Washington has ordered more troops to the region, with some set to arrive before week's end. "If Iran fails to accept the reality of the current moment," Leavitt added, "Trump will ensure they are hit harder than they have ever been hit before. President Trump does not bluff and he is prepared to unleash hell." Leavitt said the administration has "always estimated approximately four-to-six weeks" for the conflict when asked if the new dates indicated Trump would look to wind down the war by that point. And she sidestepped a question about whether concluding the war was a precondition for rescheduling the Trump-Xi meeting. Trump has publicly signalled any peace agreement would have to include a prohibition on Iran ever obtaining a nuclear weapon or enriching radioactive material for civilian purposes. The US plan stipulates that the Islamic Republic dismantle its main nuclear facilities and use a reduced missile arsenal in self-defense only, according to people familiar with the matter. Iran would retain certain concessions in return, including sanctions relief. The US leader has said he hopes to reach an agreement by the end of the week. That may be difficult given the wide gaps that remain between the sides, even if talks get officially underway. It's also unclear who the US is negotiating with since several top Iranian government and military officials have been killed....