Dubai, United Arab Emirates - A U.S. Navy guided missile destroyer was left with a gaping hole on one side after it collided with an oil tanker early Sunday just outside the strategic Strait of Hormuz.

The collision left a breach about 10 feet by 10 feet in the starboard side of USS Porter. No one was injured on either vessel, the U.S. Navy said in a statement.

The collision with the Panamanian-flagged and Japanese-owned bulk oil tanker M/V Otowasan happened about 1 a.m. local time. Photos released by the Navy showed workers standing amid twisted metal and other debris hanging down from the hole.

The cause of the incident is under investigation, the Navy said, though the collision was not "combat related." There were no reports of spills or leakages from either the USS Porter or the Otowasan, the Navy said.

Navy spokesman Greg Raelson said the destroyer now is in port in Jebel Ali, Dubai. "We're just happy there were no injuries," he said. "An investigation is under way."

The USS Porter is on a scheduled deployment to the U.S. 5th Fleet, which is based in Bahrain, an island nation in the Persian Gulf, near Iran.

The Strait of Hormuz, at the mouth of the Gulf, is a crowded and tense waterway where one-fifth of the world's oil is routed. Tensions have risen there over repeated Iranian threats to block tanker traffic in retaliation for tighter sanctions by the West. The sanctions are aimed at persuading Iran to abandon its uranium enrichment program, so far without success.

Three years ago, the USS Hartford, a nuclear-powered submarine based in Groton, collided in the strait with the USS New Orleans, a San Diego-based amphibious ship.

The New Orleans' fuel tank was ruptured, and 15 sailors on the Hartford suffered minor injuries. The collision caused $2.3 million in damage to the New Orleans, and the cost so far of repairs to the Hartford is $102.6 million.

The submarine's commanding officer was relieved of his duties, and the sub's chief of the boat, an adviser to the commanding officer, was reassigned. Several crew members were punished.