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Black smoke rises following explosions near a military base hosting U.S. forces in the northern Iraqi city of Irbil, Friday.Stella Martany/The Associated Press

The U.S. military said Friday that it fired on another merchant vessel that was trying to breach its blockade of Iranian ports, while Iran targeted American strongholds around the Persian Gulf.

The U.S. and Iran showed no sign of backing away from their conflict after a 13th straight night of strikes. With fighting flaring again and diplomacy uncertain, both sides made moves suggesting an escalation was possible. U.S. embassies in the Middle East began alerting Americans in the region that options to leave could become more limited, while Iran’s Revolutionary Guard advised residents of neighbouring countries to stay away from bases with U.S. troops.

Meanwhile, Saudi Arabia struck the port city of Hodeida in Yemen in response to Iranian-backed Houthi rebel attacks on Saudi oil tankers in the Red Sea, the Saudi-led coalition in Yemen said early Saturday. The Houthis said the group would escalate after tensions have been brewing for weeks, breaking a year-long calm.

Oil retreats from above $100, but set for weekly rise on Middle East escalation

American forces disabled the M/T Lavine in the Gulf of Oman after the ship attempted to run the blockade at least four times, Capt. Tim Hawkins, U.S. Central Command spokesman, told the Associated Press. Hawkins stressed that the ship’s crew was warned and didn’t comply with commands. The military then fired into its engine room. It’s the second commercial ship to be disabled since the military reimposed its blockade. U.S. Central Command said it also has redirected 12 vessels.

The same day the naval blockade was reimposed, the U.S. military said it opened fire on the Curacao-flagged oil tanker Belma sailing toward Kharg Island, Iran’s main oil export terminal in the Persian Gulf. After the ship “ignored multiple warnings,” a U.S. aircraft disabled the merchant vessel by firing a missile into the ship’s smokestack on July 15.

Earlier on Friday, U.S. President Donald Trump described negotiations with Iran as “by far the most serious that we’ve seen,” even as the U.S. has launched daily strikes. Trump added that he’s “not in a hurry” to end the war.

Vowing that Iran “will not bow to U.S.” bullying, Iranian Foreign Minister Abbas Araghchi noted ongoing discussions with two global powers often at odds with Americans – China and Russia – and warned in an interview with the semi-official news outlet Tasnim that the Islamic Republic is “neither intimidated by threats nor will we yield to pressure.”

At the centre of the fight is the Strait of Hormuz, a crucial passage for world energy supplies that has been effectively shut down by Iranian attacks, sending fuel prices soaring and causing widespread economic turmoil.

US strikes sites across Iran and countries in the region are targeted

In the northern Iraqi city of Irbil, which is home to a contingent of American military advisers, security officials said Friday that U.S.-led forces had shot down five explosive-laden drones. Repeated blasts echoed in Irbil, the capital of Iraq’s semi-autonomous Kurdish region, and plumes of black smoke were seen near its airport, where U.S. forces are based. U.S. military officials did not respond to a request for comment on the apparent attacks.

Explainer: Why are Iran and the U.S. trading blows again?

Meanwhile, Iran’s Revolutionary Guard said it had targeted the U.S. base in Udairi, Kuwait, setting ablaze and destroying three ammunition and storage sheds. It also claimed to have struck a watchtower for the U.S. Navy’s Fifth Fleet, based in Bahrain, which it said was damaged.

U.S. Central Command did not respond to inquiries about the claims.

Both Bahrain and Jordan said they had intercepted aerial attacks by Iran on Friday.

As a barrage of assaults was aimed at bases of the United States and its allies, the U.S. hit a Revolutionary Guard naval base in northern Iran, according to the semi-official news outlets Fars and ISNA. Blasts from U.S. bombardment were also reported on Iran’s Qeshm Island, a base for naval assets including drone boats that Iran can use to attack vessels in the strait, as well as in Isfahan province, home to a major Iranian air base and one of Iran’s nuclear sites.

Additional strikes reportedly hit Iran’s southwest Khuzestan province and southern Fars province.

Central Command said the latest barrage was designed to “further degrade Iran’s ability to threaten civilian mariners and commercial vessels transiting regional waters” as the Americans push to reopen the strait, through which one-fifth of the world’s oil and gas transited in peacetime.

Houthi attacks give Iran more leverage in potential negotiations

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Houthi supporters rally against the Saudi-led coalition's restrictions on Houthi-controlled areas, in Sanaa, Yemen, July 17.Khaled Abdullah/Reuters

A diplomatic delegation from Oman, which has been involved in mediation efforts between the U.S. and Iran, was in Tehran on Friday to discuss managing shipping traffic in the strait, according to Iran’s state news agency.

Iran’s ability to effectively close the strait – and cause economic chaos far beyond the Middle East – gives it tremendous leverage in negotiations. Its Houthi allies increased that leverage when they targeted two Saudi oil tankers in the Red Sea on Thursday – increasing the risks of shipping through another vital route for Middle Eastern oil. The attacks made good on the Houthis’ threat to close the Bab el-Mandeb Strait to Saudi-linked shipping.

An official at the Transport General Authority also said a Saudi vessel was targeted Friday while sailing in the Red Sea, resulting in minor damage to its hull, according to the Saudi Press Agency.

Houthi-run Al Masirah television said early Saturday that Saudi strikes hit facilities belonging to the state telecommunications corporation and also targeted Kamaran island, off Yemen’s western coast. The broadcaster said one employee was injured and a woman was also wounded in Kamaran Island.

Saudi Arabia said it would do everything necessary to protect its ships and warned the Houthis if they continued “hostile acts then there will be no hesitation in responding.”

The strait at the southern tip of the Arabian Peninsula connects the Red Sea to the Gulf of Aden, and around 12 per cent of the world’s trade, including one-fourth of global container traffic, passes through there.

The price of Brent crude oil, the international standard, dipped slightly Friday to about US$96, but it is still up substantially from before the start of the war, when it was trading around US$72 a barrel. Motorists in the U.S. saw gas prices tick up to an average of US$4.11 a gallon, AAA said.

What happens if the Red Sea and Strait of Hormuz are blocked?

Reuters

No signs of diplomatic breakthrough as war’s human toll expands

Beyond the economic impact, the human toll was also apparent, with the Iranian Health Ministry reporting that 3,434 people have been killed since the war began.

In other developments, the International Maritime Organization said at least 6,000 mariners were stranded on about 400 vessels around the Strait of Hormuz. UN human rights chief Volker Türk called for “urgent action” to help them. His office said the seafarers are exposed to the fighting and some have been abandoned by their ships’ owners, leaving them to “fend for themselves without food, water, fuel, medical care, electricity or means to communicate with their families.”

There have been no public signs of progress in any negotiation efforts.

Opinion: Yet another shipping route gets blocked. Welcome to the new reality

Foreign Minister Ishaq Dar of Pakistan, which has played a significant role in previous negotiations, met his Iranian counterpart, Araghchi, on Friday. But before the meeting, Araghchi appeared to brush off any attempts at mediation, saying he did not think the conflict needed more mediators, instead insisting the U.S. must change its position.

The U.S. and Israel attacked Iran on Feb. 28 and have offered shifting goals for the war, including toppling Tehran’s government and eliminating its nuclear program.

Israel signalled its willingness to rejoin the conflict in recent days. Prime Minister Benjamin Netanyahu’s office said he would travel to the U.S. next week and meet with Trump.

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