The U.S. military has released its first official account of Iran's 15-hour detention of 10 U.S. sailors whose boats had strayed into Iranian waters in the Persian Gulf last week.

A U.S. Central Command statement said the two Navy vessels were scheduled to meet up with a U.S. Coast Guard boat in international waters for refueling but deviated from their planned course on the way.

"The command investigation will determine what caused the change in course and why the RCBs (U.S. Navy boats) entered into Iranian territorial waters in the vicinity of Farsi Island," the statement said.

The sailors were traveling through the Persian Gulf from Kuwait toward Bahrain when U.S. controllers lost contact with them Tuesday.

One of the boats "had indications of a mechanical issue in a diesel engine," and both vessels stopped, CENTCOM said. "This stop occurred in Iranian territorial waters, although it's not clear the crew was aware of their exact location. While the RCBs were stopped and the crew was attempting to evaluate the mechanical issue, Iranian boats approached the vessels."

The sailors were later detained.

"At gunpoint, the RCBs were escorted to a small port facility on Farsi Island where the U.S. sailors disembarked and were detained for approximately 15 hours. At this point there are no indications that the sailors were physically harmed during their detainment," CENTCOM said.

U.S. Secretary of State John Kerry, who spoke to his Iranian counterpart several times over the incident, said the swift release of the sailors was a success for diplomacy.

At the same time, Kerry says the pictures of 10 American sailors being detained by Iran last week left him extremely upset and frustrated.

Kerry praised Zarif and Iranian President Hassan Rouhani for "responding promptly" to the situation, saying that what could have been a very dangerous major hostage crisis just a few years ago was resolved quickly because of diplomacy.

Kerry answered critics of U.S. policy toward Iran by saying it is far more dangerous not to negotiate with Tehran.

By VoA News