NORFOLK - The submarine Newport News was submerged and leaving the Persian Gulf when a mammoth Japanese oil tanker passed overhead at a high speed, creating a sucking effect that made the sub rise and hit the ship, the Navy said Tuesday.

That is the preliminary finding of Monday's collision between the Norfolk-based submarine and the Mogamigawa, a 1,100-foot-long merchant ship displacing 300,000 tons.

Both were southbound, crossing the busy and narrow Strait of Hormuz while heading into the Arabian Sea.

"As the ship passed over the sub, it ended up sucking the submarine into it," said Lt. Cmdr. Chris Loundermon, a spokesman for Submarine Force in Norfolk.

"It is a principle called the venturi effect," he said.

The Mogamigawa, built in 2001, is a super tanker that displaces 300,000 tons of water - three times the amount of water of a modern aircraft carrier.

The Newport News, a Los Angeles-class submarine, displaces 6,900 tons of water.

"This was a very, very large ship moving at higher speed," Loundermon said.

No one was injured aboard either ship, the Navy said, and damage to both vessels is relatively minor.

The collision was the fifth involving a U.S. submarine in the past six years, according to news records.

Four of those incidents involved other surface ships. In one case, a submarine hit an undersea mountain.

The Newport News collided with the Mogamigawa while submerged in the Arabian Sea about 10:30 p.m. local time, the Navy said.

Afterward, it was going to Bahrain to check for further damage.

"She is headed to port right now," Cmdr. Kevin Aandahl, a spokesman for the U.S. Naval Forces Central Command in Bahrain, said late Tuesday from Bahrain.

Damage to the Norfolk-based Newport News appears to be confined to the bow, he said. The sail, or mast, and the sub's nuclear reactor were unharmed, he said.

Aand ahl said he could not discuss details such as the speed or depth of the submarine at the time of the impact.

Aandahl emphasized that the Newport News was not surfacing at the time, as was reported earlier by CNN.

The Strait of Hormuz separates the Arabian Gulf from the Gulf of Oman and the North Arabian Sea. It is about 40 miles wide - 34 miles wide at its narrowest point, according to globalsecurity.org.

The strait, which is the world's most important oil chokepoint, has channels for inbound and outbound tanker traffic that are 2 miles wide, as well as a buffer zone of 2 miles, according to the Web site.

The Newport News left Norfolk along with the aircraft carrier Eisenhower strike group in October for a six-month deployment to the Middle East.

The Mogamigawa was traveling from the Persian Gulf to Singapore with a crew of eight Japanese members and 16 Filipino members. The submarine has a crew of about 130.

The other four submarine collisions in the past six years are: