GENEVA (AP) — Iran announced the temporary closure of the Strait of Hormuz on Tuesday for live fire drills in a rare show of force as its negotiators held another round of indirect talks with the United States over the Islamic Republic’s disputed nuclear program.

It was the first time Iran has announced the closure of the key international waterway, through which 20% of the world’s oil passes, since the U.S. began threatening Iran and rushing military assets to the region. It was not immediately clear if the strait had been closed, but such a rare and perhaps unprecedented move could further escalate tensions that threaten to ignite another war in the Middle East.

As the talks began, Iran’s state media announced that Iranian forces had fired live missiles toward the strait and would close it for several hours for “safety and maritime concerns.”

Supreme Leader Ayatollah Ali Khamenei meanwhile warned that “the strongest army in the world might sometimes receive such a slap that it cannot get back on its feet.”

Iranian diplomat sees ‘new window’ in talks

Iran’s foreign minister later adopted a different tone, expressing optimism about the talks and saying “a new window has opened” for reaching an agreement.

“We are hopeful that negotiations will lead to a sustainable and negotiated solution which can serve the interests of relevant parties and the broader region,” Abbas Araghchi told a U.N. disarmament conference after leading the Iranian delegation at the talks held in Geneva.

He added that Iran “remains fully prepared to defend itself against any threat or act of aggression,” and that the consequences of any attack on Iran would not be confined to its borders.

He made no specific mention of the military drills or the closure of the Strait of Hormuz.

U.S. President Donald Trump, who scrapped an earlier nuclear agreement with Iran during his first term, has repeatedly threatened to use force to compel Iran to agree to constrain its nuclear program. Iran has said it would respond with an attack of its own. Trump has also threatened Iran over the killing of protesters.

Vance says talks went well ‘in some ways’

Trump’s envoys, Steve Witkoff and Jared Kushner, led the U.S. delegation at the latest indirect talks, held inside the residence of the Omani envoy to Geneva. Oman, a longtime regional mediator, had hosted an earlier round on Feb. 6.

There was progress in the talks but many details remained to be discussed, according to a U.S. official who was not authorized to comment publicly and spoke on condition of anonymity. The Iranian delegation said they would present more detailed proposals in the next two weeks to narrow gaps, the official said.

“In some ways, it went well,” U.S. Vice President JD Vance said in an interview with Fox News Channel after he spoke with Witkoff and Kushner. “But in other ways, it was very clear that the president has set some red lines that the Iranians are not yet willing to actually acknowledge and work through.”

The U.S. also hosted talks between envoys from Russia and Ukraine in Geneva on Tuesday and Wednesday, days ahead of the fourth anniversary of the all-out Russian invasion of its neighbor.

Araghchi, who led the Iranian side, also said he met with Director-General Rafael Grossi of the International Atomic Energy Agency on Monday in Geneva. The Iranian minister said they discussed the agency’s role in helping to achieve an agreement.

A live fire drill

Iran said its Revolutionary Guard started a drill early Monday in the Strait of Hormuz, the Persian Gulf and the Gulf of Oman, which are crucial international shipping routes. It was the second time in recent weeks that Iran has held a live fire drill in the Strait of Hormuz.

Iran often carries out military drills in the strait that can impede maritime traffic, but the announced closure went a step further. Danny Citrinowicz, an Iran expert at Israel’s Institute for National Security Studies, said Iran last closed the strait during the war with Iraq in the 1980s, when it mined the waterway.

He said the latest announcement was a message to the international community that any strike on Iran would have global impact.

Oil prices fell after the talks concluded. US oil was down 1.3% at $62.06 per barrel while international benchmark Brent crude was off fully 2.3% at $67.03 per barrel. Oil prices had risen several dollars per barrel after Trump began bolstering the U.S. military presence in the Middle East, but remain subdued on expectation that an eventual deal would send prices lower.

Khamenei meanwhile stepped up his warnings to the U.S. over its military buildup.

“Of course a warship is a dangerous apparatus, but more dangerous than the warship is the weapon that can sink the warship,” Khamenei said, according to Iranian state TV. He also warned the U.S. against “forcing the result of talks in advance.”

US increases military presence

Last week, Trump said the USS Gerald R. Ford, the world’s largest aircraft carrier, was being sent to the Mideast. It will join the USS Abraham Lincoln and its accompanying guided-missile destroyers, which have been in the region for three weeks.

The USS Gerald R. Ford and its escort of three destroyers are now in the mid-Atlantic after being ordered to depart the Caribbean for the Middle East last week, a Navy official confirmed Tuesday.

The official, who spoke on condition of anonymity to discuss sensitive ship movements, said the Ford, along with the destroyers USS Mahan, Bainbridge, and Winston Churchill, are in the mid-Atlantic and no longer with the U.S. Southern Command’s area of operations.

Given its current location, the Ford and its escorts are likely more than a week away from reaching the waters off the coast of Iran.

U.S. forces shot down an Iranian drone that approached the Lincoln on the same day last week that Iran tried to stop a U.S.-flagged ship in the Strait of Hormuz.

Gulf Arab nations have warned any attack could spiral into another regional conflict in a Mideast still reeling from the Israel-Hamas war.

The Trump administration is seeking a deal to limit Iran’s nuclear program and ensure it does not develop nuclear weapons. Iran says it is not pursuing weapons and has so far resisted demands that it halt uranium enrichment on its soil or hand over its stockpile of highly-enriched uranium.

The U.S. and Iran were in the middle of months of meetings when Israel’s launch of a 12-day war against Iran back in June halted the talks. The U.S. bombed Iranian nuclear sites during that war, likely destroying many of the centrifuges that spun uranium to near weapons-grade purity. Israel’s attacks decimated Iran’s air defenses and targeted its ballistic missile arsenal as well.

Before the June war, Iran had been enriching uranium up to 60% purity, a short, technical step away from weapons-grade levels.

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This story has been corrected to fix a misspelling of Khamenei.

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Liechtenstein reported from Vienna. Associated Press writers Melanie Lidman in Tel Aviv, Israel; Michelle L. Price, Darlene Superville and Konstantin Toropin in Washington, Farnoush Amiri at the United Nations and David McHugh in Frankfurt, Germany, contributed to this report.

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