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In this photo released by state-run IRIB News Agency, an oil tanker is on fire in the sea of Oman, Thursday, June 13, 2019. Two oil tankers near the strategic Strait of Hormuz have been reportedly attacked. The alleged assault on Thursday left one ablaze and adrift as sailors were evacuated from both vessels. The U.S. Navy rushed to assist amid heightened tensions between Washington and Tehran.

DUBAI, United Arab Emirates — Two oil tankers near the strategic Strait of Hormuz were damaged in suspected attacks on Thursday, an assault that left one ablaze and adrift as sailors were evacuated from both vessels and the U.S. Navy rushed to assist amid heightened tensions between Washington and Tehran.

The Navy and the ship's owners offered no immediate explanation on what weapon caused the damage to the MT Front Altair and the Kokuka Courageous in the Gulf of Oman off the coast of Iran, though all believed the ships had been targeted in an attack.

It marks the latest mysterious incident to target the region's oil tankers. The U.S. alleged that Iran used limpet mines to attack four oil tankers off the nearby Emirati port of Fujairah last month. Iran has denied being involved, but it comes as Iranian-backed rebels in Yemen also have launched missile and drone attacks on Saudi Arabia.

Meanwhile in Iran, Supreme Leader Ayatollah Ali Khamenei warned that while Tehran doesn't seek nuclear weapons, "America could not do anything" to stop Iran if it did.

The comments came during a one-on-one meeting capping Japanese Prime Minister Shinzo Abe's high-stakes visit in Tehran that sought to ease Iran-U.S. tensions, suggested the efforts had failed.

Benchmark Brent crude spiked at one point by as much 4% in trading following the suspected attack, to over $62 a barrel, highlighting how crucial the area remains to global energy supplies. A third of all oil traded by sea passes through the strait, which is the narrow mouth of the Persian Gulf.

Cmdr. Joshua Frey, a 5th Fleet spokesman, said the U.S. Navy was assisting the two vessels that he described as being hit in a "reported attack." He did not say how the ships were attacked or who was suspected of being behind the assault.

Dryad Global, a maritime intelligence firm, preliminarily identified one of the vessels involved as the MT Front Altair, a Marshall Islands-flagged crude oil tanker. The vessel was "on fire and adrift," Dryad added. It did not offer a cause for the incident or mention the second ship.

The firm that operates the Front Altair told The Associated Press that an explosion was the cause of the fire onboard. International Tanker Management declined to comment further saying they are still investigating what caused the explosion. Its crew of 23 is safe after being evacuated by the nearby Hyundai Dubai vessel, it said.

The second vessel was identified as the Kokuka Courageous. BSM Ship Management said it sustained hull damage and 21 sailors had been evacuated, with one suffering minor injuries. Iranian state television said 44 sailors from the two tankers have been transferred to an Iranian port in the southern province of Hormozgan.

The timing of Thursday's suspected attack was especially sensitive as Abe's high-stakes diplomacy mission was underway in Iran. Japan's Trade Ministry said the two vessels had "Japan-related cargo."