The United Arab Emirates said Friday that a Japanese oil tanker was hit by an explosives-laden dinghy in the Persian Gulf in what would be the first attack in the strategic waterway where millions of barrels of oil are transported each day.
The report — which came days after an al-Qaida-linked group claimed responsibility for attacking the vessel — raised fears about the vulnerability of the Strait of Hormuz, a vital shipping lane for many petroleum exporting countries.
It was the latest in what has been a series of conflicting accounts of what happened to the M. Star supertanker, which was damaged as it entered the Strait of Hormuz, a transit point for about 40 percent of oil shipped by tankers worldwide.
Al-Qaida has carried out attacks on oil infrastructure on land in nearby Saudi Arabia, as well as a 2002 suicide bombing of the Limburg off the coast of Yemen and the 2000 bombing of the USS Cole in the Yemeni port of Aden.
But if the UAE report is confirmed, the July 28 incident would be the first militant attack in the strait, a narrow chokepoint between Oman and Iran. For years, fears have been high that the waterway could be the site of conflict between the United States and Iran, but the reported attack underscored concerns that militant groups could target civilian vessels to foment economic instability.
While the ship's owner, Mitsui O.S.K. Lines, initially said it suspected an attack, others said it was hit by a large wave or was involved in a collision with another vessel. A crew member was injured and the tanker sustained a square-shaped dent on the rear side of the hull.
"The attack is not a major attack in terms of its target. But the geography is really worrying," said Mustafa Alani, director of national security and terrorism studies for the Dubai-based Gulf Research Center. "Now, they are able to attack outside the Strait of Hormuz where 17 million barrels of oil a day are transported. The fact that they are able to do this is a wake up call."
The Emirati state news agency WAM said Friday that a boat piled with explosives struck the tanker — the first official word that the incident was an attack.
WAM, quoting an unnamed government official, said traces of homemade explosives were found on the hull of the tanker. Investigators believe a small boat with explosives had approached the tanker, indicating the vessel had been "subjected to a terror attack," the news agency said.
On Wednesday, a group known as the Abdullah Azzam Brigades said it had carried out a suicide attack against the tanker to avenge the plunder of Muslim wealth and to destabilize international markets. The statement was issued by al-Qaida's communications wing, the al-Fajr Media Center and posted on militant websites.
It included a photo of the purported suicide bomber pointing to a photograph of a tanker on a laptop. It said it had delayed the announcement until several group members involved in the operation "returned safely to base."
The Abdullah Azzam Brigades has in the past claimed responsibility for several attacks, including the August 2005 firing of Katyusha rockets that narrowly missed a U.S. amphibious assault ship docked at Jordan's Aqaba Red Sea resort but killed a Jordanian soldier.
The group also has claimed it was behind the July and October 2004 bombings at Egypt's Red Sea resort of Sharm el-Sheik and two other resorts that killed a total of 98 people.
Abdullah Azzam Brigades operates under the al-Qaida umbrella but consists of different cells that are not directly controlled by the terror network, according to Evan Kohlmann, a terrorism analyst with New York-based security consultancy Flashpoint Global Partners. He said the network has long talked of attacking "the economic lifelines and infrastructure in this region."
"They have gone from rocket attacks in Lebanon and now moved into a suicide, boat bombings attack on an oil tanker," Kohlmann said. "It's an escalation. It may not be the most sophisticated attack we have ever seen. But it is an escalation."
He said the Yemen-based al-Qaida in the Arabian Peninsula has called for attacks in the Persian Gulf at least four times in the past six months, including mentions in its magazine as well as in .
Kamran Bokhari, an analyst with STRATFOR, a private security think tank in Austin, Texas, said he remained unconvinced that it was a terrorist attack, in part because of the cautious Japanese response. "It's not clear at all this is an attack and thus far it is a mysterious event," he said.
Japan's Transport Minister Seiji Maehara said Friday he has instructed diplomatic channels to confirm WAM's report with Emirati officials. Japan's official in charge of maritime safety, Hiroaki Sakashita, said the ministry has collected evidence and samples, including residue left on affected parts of the tanker for its own independent investigation.
"First we will analyze everything we obtained before making any judgment," Sakashita said.
Lt. John Fage, a spokesman for the U.S. Navy's Fifth Fleet in Bahrain, said Friday that a team of Navy divers had examined the ship. But he had no further information on the UAE claims.
The ship, loaded with 270,000 tons of oil, was heading from the petroleum port of Das Island in the United Arab Emirates to the Japanese port of Chiba outside Tokyo. WAM reported that the vessel left the Emirati port of Fujairah on Friday after damages to the hull were repaired.