Two oil tankers were targeted in the Gulf of Oman. The Japanese foreign ministry says the vessels were carrying "Japan-related" cargo. All crew members were safely rescued.
US Secretary of State Mike Pompeo said on Thursday that Washington has assessed, based on intelligence, type of weapons used and level of expertise needed, that Iran is responsible for the attacks on tankers in the Gulf of Oman.
He offered no concrete evidence to back up the assertion.
"It is the assessment of the United States government that the Islamic Republic of Iran is responsible for the attacks that occurred in the Gulf of Oman today," Pompeo told reporters.
"This assessment is based on intelligence, the weapons used, the level of expertise needed to execute the operation, recent similar Iranian attacks on shipping, and the fact that no proxy group operating in the area has the resources and proficiency to act with such a high degree of sophistication," Pompeo said.
Early Friday morning, the US military's Central Command released a video it says shows Iranian forces removing an unexploded limpet mine from one of the two ships suspected to have been attacked near the Strait of Hormuz.
Capt. Bill Urban, a Central Command spokesman, said a Revolutionary Guard patrol ship removed the limpet mine from the Kokuka Courageous.
Iran categorically rejected the "unfounded" US claim over the oil tanker attacks, Iran's mission to the United Nations said after Washington blamed Tehran for the attacks.
"Iran categorically rejects the US unfounded claim with regard to 13 June oil tanker incidents and condemns it in the strongest possible terms," the Iranian mission said in a statement.
Saudi Arabia said it agrees with the United States that Iran was behind the suspected attacks on two oil tankers in the Gulf of Oman.
"We have no reason to disagree with the secretary of state. We agree with him," Saudi Minister of State for Foreign Affairs Adel al Jubeir told CNN.
"Iran has a history of doing this."
The United Arab Emirates' Minister of State for Foreign Affairs said attacks on oil tankers in the Gulf of Oman and on a Saudi airport are a 'major and dangerous escalation' that requires the international community to scramble to protect regional stability and security.
"Wisdom and collective responsibility are needed to prevent more escalation," Anwar Gargash said in a Twitter post.
Two oil tankers in the Gulf of Oman, near the strategic Strait of Hormuz, were attacked on Thursday, the US Navy said, with one adrift and on fire amid heightened tensions between Washington and Tehran and a high-stakes visit by the Japanese prime minister to Iran.
The latest incident comes after the US alleged that Iran used mines to attack four oil tankers off the nearby Emirati port of Fujairah last month.
The tanker association INTERTANKO said two vessels had been attacked in the Middle East and there were growing worries for the safety of ships and their crews sailing through the Strait of Hormuz.
Senior US officials said they do not believe the threat from Iran is over, adding the US photographed an unexploded mine on the side of one of the tankers and assessed Iran was responsible for the attack. The photograph is expected to be made public later Thursday.
US Central Command said in a statement the destroyer USS Mason was en route to the scene of the attacks. The destroyer USS Bainbridge remains in close contact with the damaged tanker M/V Kokuka Courageous and will tolerate no interference, the statement said.
The US military added that it has no interest in engaging in a new conflict in the Middle East but will defend American interests including freedom of navigation.
Japan's trade ministry says the two oil tankers reportedly attacked near the Strait of Hormuz carried "Japan-related" cargo.
Japanese operator Kokuka Sangyo confirmed one of its tankers carrying methanol came under fire in the Gulf of Oman.
The owner of the Marshal Islands-flagged Front Altair, which was loaded with 75,000 tonnes of flammable oil naphtha, refuted Iranian reports that it had sunk.
Earlier this morning, two #tankers, #FrontAltair & #Kokuka Courageous, were reportedly torpedoed off the coast of #Oman. Watch their final movements before the reported #incidents in this past track video and learn more here: https://t.co/Odj8NYkkSm #marinetraffic pic.twitter.com/78XRuBorut— MarineTraffic (@MarineTraffic) June 13, 2019
All the crew were saved after abandoning Kokuka Courageous ship and its methanol cargo is intact, Kokuka Sangyo shipping company said. It was going from Saudi Arabia to Singapore.
At least 21 sailors were evacuated off the Kokuka. One sailor was slightly injured and the Pamana-flagged ship sustained hull damage.
"It appears other ships also came under fire," company president Yutaka Katada told reporters in Tokyo, confirming an earlier report from its Singapore parent company about a "security incident" in the busy shipping waterway.
The Norwegian shipping firm Frontline confirmed that its oil tanker Front Altair was on fire, Norwegian newspaper VG reported earlier in the day, quoting a company spokesman.
All 23 crew members from the Marshal Islands-flagged tanker were brought to safety at a nearby vessel, the spokesman added
Iran rescued 44 crew members after the tanker "accident," IRNA state media reported.
Iranian state TV's website, citing the pro-Iran Lebanese satellite news channel Al Mayadeen, said earlier two oil tankers had been targeted in the Gulf of Oman. It offered no evidence to support the claim.
The United Kingdom Maritime Trade Operations, which is run by the British navy, put out the alert but did not elaborate on the incident. It said it was investigating.
The coordinates offered for the incident by the UK group put it some 45 kilometres (25 miles) off the Iranian coastline.
"Following two attacks on Member vessels this morning, I am extremely worried about the safety of our crews going through the Strait of Hormuz," Paolo d’Amico, chairman of INTERTANKO, said in a statement.
"We need to remember that some 30% of the world’s (seaborne) crude oil passes through the Straits. If the waters are becoming unsafe, the supply to the entire Western world could be at risk," Amico said.
INTERTANKO represents the greater part of the world's independent tanker fleet.
Benchmark Brent crude spiked 4 percent in trading following the reported attack, to over $62 a barrel, according to early market figures.
The area is near the Strait of Hormuz, a major strategic waterway through which a fifth of global oil consumption passes from Middle East producers.
There was no immediate confirmation from ship operators or authorities in Oman or the United Arab Emirates (UAE), in whose territorial waters four tankers were hit last month.
The shipping newspaper Tradewinds reported that a tanker owned by Norway's Frontline had been struck by a torpedo off the coast of Fujairah, one of the Emirates in the UAE. It cited unnamed industry sources.
Frontline later confirmed that its tanker Front Altair was on fire after the incident.
London-based journalist Tara Kangarlou joins TRT World for more on the story.
Trifecta of rising tensions
The attacks the US blamed on Iran in May occurred off the Emirati port of Fujairah, also on the Gulf of Oman, approaching the critical Strait of Hormuz, the narrow mouth of the Persian Gulf through which a third of all oil traded by sea passes.
The Thursday attack timing was especially sensitive as Japanese Prime Minister Shinzo Abe was visiting Iran on a high-stakes diplomacy mission.
On Wednesday, after talks with Iranian President Hassan Rouhani, Abe warned that any "accidental conflict" that could be sparked amid the heightened US-Iran tensions must be avoided.
His message came just hours after Yemen's Iranian-backed Houthi rebels attacked a Saudi airport, wounding 26 people.
Riyadh accused Tehran of ordering the attack. Houthi-related media said the Saudi-led coalition retaliated on Thursday with air strikes on the capital Sanaa.
Meanwhile, in Tokyo, Japan's Chief Cabinet Secretary Yoshihide Suga, a top government spokesman, told reporters that Abe's trip was intended to help de-escalate tensions in the Mideast — but not specifically mediate between Tehran and Washington.
His remarks were apparently meant to downplay and lower expectations amid uncertain prospects for Abe's mission.
Tensions have escalated in the Mideast as Iran appears poised to break the 2015 nuclear deal with world powers, prompted by the Trump administration's pull out last year.
The world cannot afford a major confrontation in the Gulf, UN chief Antonio Guterres warned on Thursday, as the Security Council prepared to meet to discuss suspected attacks on two oil tankers in the strategic sea lane.
“I strongly condemn any attack against civilian vessels,” the UN secretary general told a Security Council meeting on UN cooperation with the Arab League.
"Facts must be established and responsibilities clarified," he said.
"If there is something the world cannot afford, it is a major confrontation in the Gulf region."