A sea mine may have been responsible for denting a 160,000-ton Japanese oil tanker in the Strait of Hormuz this week, investigators in the United Arab Emirates said Thursday, although the boat's owner maintains it was likely attacked.

There is still much conflicting speculation about what punched a large dent into the side of the M Star tanker, which was on its way back to Japan after filling up in the UAE. Earlier reports that a freak wave smacked the ship have been dismissed, while boat owner Mitsui O.S.K. Lines maintains that its vessel was probably attacked. (See company statement.)

Crewmen reported seeing a flash of light on the horizon just before an explosion.

Some are pointing fingers at Iran, as it carefully guards its territorial waters and laid thousands of floating mines for that purpose during the Iran-Iraq war – some of which remain today. This week's incident occurred near where five armed Iranian fast boats confronted a flotilla of US Navy ships in 2008 while on patrol about 12 miles from Iranian territory in the Strait of Hormuz, sparking a confrontation.

The M Star is currently being inspected at the UAE port of Fujairah. No oil has leaked from the ship since it was struck in the early hours of Wednesday morning in Omani waters. But the hull was found to be punctured about four meters above the waterline, reports The National in Dubai. The newspaper also quoted a local expert as saying that a collision was not a possibility, and another ruled out a rocket grenade attack.

Mustafa Alani, a senior adviser on terrorism and security at the Gulf Research Center in Dubai, said the damage to the ship’s starboard, near the stern, appeared to match that of a floating mine. Although sea mines were designed to cause more damage, one that was 20 years old would have lost some of its potency, he said.

“They tried to clear as many as possible, but there were many thousands put down during the Iran-Iraq war,” Mr. Alani said.

“It’s not a [rocket-propelled grenade]. The collapsed area, if it were an RPG, would be a round spot. There would be more blackness. It doesn’t look like there was a direct impact point, which you would see with an RPG.” The damage at the water level also indicated a mine, he added.

Japan’s English-language Daily Yomiuri quoted “a high-ranking Maritime Self-Defense Force firearms expert” as saying that a small boat collision was highly likely. But a Japanese Coast Guard official told the newspaper that, because the dent was higher than the water line, a collision seemed improbable. Siding with that view, the US Navy's 5th Fleet, which patrols the region, told The Associated Press it had ruled out a collision with any of its vessels.

A Reuters analysis argues that conditions at sea can make it difficult to determine precisely what happened in any given incident.

As with the sinking of a South Korean warship in March, the hijacking of the freighter Arctic Sea last year or even the Gulf of Tonkin incident that helped spark the Vietnam war, getting to the truth of what happened could prove hard or impossible. ...

"In international waters, it is always difficult to tell what happened," said Jonathan Wood, global issues analyst at Control Risks. "It could be an accident or it could be an attack. If you are an investor, there is not much you can do except sit and wait and watch the news and market reaction."

... Attacks on land are hard enough to probe, but at sea independent witnesses may be scarce, radar and satellite coverage patchy and physical evidence at the bottom of the sea.

Attacks are rare in the Strait of Hormuz, a passage through which 40 percent of the world’s oil is shipped. In 1987 a US-chartered tanker was struck by a mine near Fujairah amid the Iran-Iraq war, causing an oil spill, The Christian Science Monitor reported at the time. Shippers worried about the safety of their vessels in the Persian Gulf as Iraq stepped up attacks on its neighbor.

Now, Iranian threats to close off the strait in retaliation against economic sanctions may be a bigger threat. A senior Iranian official has warned that Tehran “will act correspondingly in the world's most strategic waterway if its enemies decide to make global shipping routes unsafe for the country's cargo ships,” the Arabic-language Fars news agency reports, according to Press TV. 

All republished content that appears on Truthout has been obtained by permission or license.