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Mourners gather near a giant billboard depicting Iran's slain supreme leader Ali Khamenei at Enghelab Square in Tehran on Monday.WAKIL KOHSAR/AFP/Getty Images

The U.S. military unleashed a new wave of strikes against Iran on Tuesday and revoked a license allowing the country to sell oil after three tankers were hit in the Strait of Hormuz, putting pressure on an already fragile ceasefire.

After a day in which huge crowds mourned Iran’s slain Supreme Leader Ayatollah Ali Khamenei in the holy city of Qom, U.S. Central Command announced that it had begun a series of strikes intended to impose what it called heavy costs. “Iran’s demonstrated aggression was unwarranted, dangerous, and a clear violation of the ceasefire,” CENTCOM said on X.

Iranian media reported explosions early Wednesday local time in the southern port city of Sirik, on Qeshm Island and in Bandar Abbas. The reports said strikes hit a commercial pier in Sirik and fishing piers in both Sirik and Bandar Abbas.

A U.S. official told Reuters that strikes targeted Iranian air defence systems, coastal surveillance systems, surface-to-air missiles, anti-ship cruise missiles and drone launch sites.

The incidents were only the latest threat to the ceasefire agreement the U.S. and Iran struck last month, pausing the conflict that started in February with U.S. and Israeli strikes across the Islamic Republic. In a potentially major blow to that agreement, Washington moved on Tuesday to withdraw a key concession that had allowed Iran to sell oil on international markets.

Oil prices rose more than three per cent after the U.S. announced the move.

Trump threatens to ‘finish the job,’ if Iran deal not reached

A U.S. official said earlier negotiators continued to work in good faith toward a final agreement with Iran. But control of the strait has given Tehran immense leverage, effectively allowing it to force a stalemate with the world’s most powerful military. Analysts say Tehran is using attacks on ships to underscore that leverage as it negotiates a long-term peace deal with the U.S.

Under the interim U.S.-Iran agreement, the U.S. Treasury issued a June 22 general license to allow the sale of crude oil and petrochemical and petroleum products of Iranian origin through August 21. In revoking that license on Tuesday, it gave Iran until July 17 to wind down any transactions.

Iran’s foreign ministry condemned the move as a breach of the framework agreement to end the war and said Washington would bear responsibility for the consequences.

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People walk near a banner depicting U.S. President Donald Trump and Israeli Prime Minister Benjamin Netanyahu, as they attend a funeral procession for Iran's late Supreme Leader Ayatollah Ali Khamenei, in Tehran on Monday.Murad Sezer/Reuters

The ministry said early on Wednesday that Iran would take any measure it deemed necessary to safeguard its interests and national security.

Qatar blamed Iran for attacking the vessels, including the huge Qatari liquefied natural gas tanker, the Al Rekayyat, which reported being struck overnight by a drone that caused a fire in its engine room. The crew were safe and being evacuated.

A Saudi-flagged crude oil tanker, believed to be the supertanker Wedyan, was also damaged off Oman, maritime security sources said. The cause was not immediately clear.

Qatar’s foreign ministry said it had summoned Iran’s deputy ambassador and handed him a protest note following the attack on the tanker.

Iran’s foreign ministry said Qatar’s accusations were perplexing and that Tehran was diligently fulfilling its commitments but asserted that commercial vessels faced risks for using routes not coordinated with Iran.

A second U.S. official, speaking on condition of anonymity, said initial indications were that Iran had fired at three commercial vessels.

Iran’s clerical rulers aim to install a permanent system to collect fees in what would amount to a huge shift of the balance of power in a region where Washington has long acted as guarantor of security.

At home, the leadership has used the mourning for Mr. Khamenei that began last week to show its control after Mr. Khamenei was killed with his daughter, granddaughter, son-in-law and daughter-in-law on the war’s first day.

The caskets of the slain leader and family were driven through the streets of the seminary city of Qom on Tuesday, where many hundreds of thousands of people carried flags and banners comparing Khamenei to revered Shi’ite martyrs.

In chants they vowed to avenge Mr. Khamenei. Some bore placards and banners reading “KILL TRUMP.”

Later on Tuesday Iranian state media showed what it said was footage of an airplane carrying Mr. Khamenei’s coffin at the airport of the Shi’ite holy shrine city of Najaf in neighbouring Iraq.

The ceasefire was intended to provide a 60-day window for negotiations on a permanent agreement, but indirect talks in Qatar ended last week with no sign of headway.

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Mourners write messages on a wall, including one in English that reads "We will kill Trump," during the funeral ceremonies for slain Iranian Supreme Leader Ayatollah Ali Khamenei and members of his family at the Imam Khomeini Mosalla Grand Mosque in Tehran, on Saturday.Altaf Qadri/The Associated Press

U.S. President Donald Trump has repeatedly threatened to resume bombing, most recently on Monday when he told reporters in the Oval Office: “We’re either going to make a deal or we’re going to finish the job...We can knock down their bridges in one hour, we can knock out their energy supply.”

Iran’s Foreign Minister Abbas Araqchi said that under the terms of the interim ceasefire memorandum, negotiations on the final deal would “not commence if threats continue.”

In launching the war four months ago, Mr. Trump said his aims were to destroy Iran’s nuclear and missile programs, end its ability to threaten its neighbours and create conditions for Iranians to topple their leaders.

None of those goals has been met, although Washington says a permanent deal will halt what it says is an Iranian program that could make a nuclear bomb, which Iran says it never sought.

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