U.S. President Donald Trump extended his deadline for Iran to reopen the crucial Strait of Hormuz to international shipping, saying Monday that the U.S. would hold off on threatened strikes against Iranian power plants for five days.

In his announcement on Truth Social, Trump also held out the possibility of a resolution to the war — though Iranian officials denied there were negotiations. Trump's turnaround appeared to offer something of a reprieve after rhetoric reached a fever pitch when the U.S. and Iran traded threats with potentially catastrophic repercussions for civilians across the region.

Shortly after Trump's announcement — hours before the deadline was set to expire — Iranian state television declared that the American leader had backed down "following Iran's firm warning."

Trump later told reporters that Iran wants "to make a deal," and claimed U.S. envoys have been holding talks with a "respected" Iranian leader. He said his Middle East special envoy Steve Witkoff and Trump's son-in-law Jared Kushner conducted talks Sunday into the evening, and that the negotiations would continue.

Trump did not name any official or officials representing Tehran. He said the U.S. has not talked to Supreme Leader Ayatollah Mojtaba Khamenei. Trump said if a deal is reached with Iran, the U.S. will move to take Iran's enriched uranium critical to its disputed nuclear program.

The war, now in its fourth week, has already seen several dramatic turning points — the killing of Iran's supreme leader, the bombing of a key Iranian gas field and strikes targeting oil and gas facilities and other civilian infrastructure in Gulf Arab nations.

The conflict has killed more than 2,000 people, shaken the global economy, sent oil prices surging and endangered some of the world's busiest air corridors.

Trump threatens to attack Iran's energy plants if Strait of Hormuz stays closed

The latest threatened attacks could have cut electricity to wide swaths of people in Iran and around the Gulf and knocked out desalination plants that provide many desert nations with drinking water. There are also increasing concerns about the consequences of any strikes on nuclear facilities.

Trump said over the weekend that the U.S. would "obliterate" Iran's power plants unless the country releases its stranglehold on the Strait of Hormuz within 48 hours — a deadline that would have expired late Monday Washington time.

But on Monday morning, Trump wrote on his Truth Social site that the U.S. and Iran have had "very good and productive conversations" that could yield "a complete and total resolution" in the war.

Trump added that the suspension of his threat to attack power plants was "subject to the success of the ongoing meetings and discussions."

The state-owned IRAN newspaper reported that Iran's Foreign Ministry denied that there have been any negotiations.

"Remarks by the U.S. president are part of efforts to reduce energy prices and buy time to implement his military plans," the newspaper said.

Earlier, Iranian Foreign Minister Abbas Araghchi said he spoke by phone with his Turkish counterpart, Hakan Fidan. Turkey has been an intermediary before in negotiations between Tehran and Washington.

Iran's paramilitary Revolutionary Guard promised retaliation if Trump made good on his threat, saying Iran would hit power plants in all areas that supply electricity to American bases, "as well as the economic, industrial and energy infrastructures in which Americans have shares."

Iranian parliament speaker Mohammad Bagher Qalibaf said Iran would consider vital infrastructure across the region to be legitimate targets, including energy and desalination facilities critical for drinking water in Gulf nations.

Iran's semiofficial Fars news agency, which is close to the Revolutionary Guard, published a list of such facilities, including the United Arab Emirates' nuclear power plant. Over the weekend, Iran launched missiles targeting Dimona in Israel, near a facility key to its long-suspected atomic weapons program. The Israeli facility wasn't damaged.

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With the U.S. deploying more amphibious assault ships and additional Marines to the Middle East, Iran also warned against any ground attack.

"Any attempt by the enemy to target Iran's coasts or islands will, naturally and in accordance with established military practice, lead to the mining of all access routes ... in the Persian Gulf and along the coasts," Iran's Defence Council warned.

Trump has said he has no plans to send ground forces into Iran but also has said he retains all options. Israel has suggested its ground forces could take part in the war.

Oil prices remained high in early trading, with the price of Brent crude, the international standard, at around $112 US a barrel, up nearly 55 per cent since Israel and the U.S. started the war on Feb. 28 by attacking Iran.

The war has also caused wild fluctuations in global stock markets, as traders grow increasingly concerned about a world energy crisis and other issues.

In addition to targeting Israel and American bases, Iran has been hitting the energy infrastructure of its Gulf Arab neighbours.

It also has a tight grip on shipping through the Strait of Hormuz, which leads from the Persian Gulf toward the open ocean and through which a fifth of the world's oil is shipped, along with other important commodities.

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A trickle of ships has been getting through the strait and Iran insists it remains open — just not to the U.S., Israel or their allies.

On Sunday, Iranian Foreign Minister Araghchi blamed the U.S. for the problem facing everyone, saying that the attack on Iran made insurance companies shut down shipping through the strait for fear of having to pay large claims if tankers were damaged or destroyed.

Iran has said it will completely close the critical waterway if Trump follows through with the threat to attack Iranian power plants.

Iranian parliament speaker Mohammad Bagher Qalibaf also said Iran would then consider vital infrastructure across the region — including energy and desalination facilities critical for drinking water in Gulf nations — legitimate targets.

Iran's death toll in the war has surpassed 1,500, its health ministry has said. In Israel, 15 people have been killed by Iranian strikes. More than a dozen civilians in the occupied West Bank and Gulf Arab states have also been killed in strikes.

In Lebanon, authorities say Israeli strikes targeting Iran-linked militia Hezbollah have killed more than 1,000 people and displaced more than a million. Meanwhile, Hezbollah has fired hundreds of rockets into Israel.