A member of the Revolutionary Guard looks out over the Persian Gulf. Tuesday, Tehran detained 10 U.S. Navy sailors after a reported mechanical problem caused one of their patrol vessels to drift into Iranian territorial waters in the gulf. Photo by Maryam Rahmanian/UPI | License Photo

TEHRAN, Jan. 12 (UPI) -- The Iranian government on Tuesday promised to return 10 U.S. Navy sailors who were detained by Tehran after mechanical trouble led one of their patrol boats to drift into the Persian Gulf.

Earlier Tuesday, the Pentagon said it had lost contact with two vessels in the waters between Kuwait and Bahrain. A short time later, Iranian officials said it was holding the vessels and the crew and assured the United States they would be "returned promptly."


The incident occurred after one of the ships experienced mechanical problems and drifted into Iranian territorial waters in the gulf -- within 12 nautical miles of the Iranian coast --- The New York Times reported. It was not immediately clear whether both ships, known as Riverine Command Boats, encountered mechanical trouble.

The incident occurred near Farsi Island, where Iran maintains a naval base.

"We were aware of circumstances surrounding a patrol in the Persian Gulf," U.S. deputy national security adviser Benjamin J. Rhodes said. "We are working to resolve the situation such that, obviously, any U.S. personnel are returned to their normal deployment."

Tehran news agency FARS reported Tuesday that the boats had traveled more than a mile into Iranian waters and that the sailors had been arrested on suspicion of "snooping" a claim it said the Islamic Revolutionary Guards Navy will be able to prove with GPS data.

Sources, however, report that communication has occurred between U.S. Secretary of State John F. Kerry and Iranian Foreign Minister Javad Zarif and that both sides expect the handover of the sailors to be complete by the end of Tuesday.

"We're expecting them sometime around sun-up," a U.S. official said in the Post report.

Small U.S. Navy boats regularly patrol international waters in the Persian Gulf.

Tuesday's incident comes three days after the Pentagon said a U.S. aircraft carrier came within about 1,500 yards of an Iranian rocket while operating in the Strait of Hormuz -- and days before full implementation was expected of the nuclear deal struck between Iran and Western powers last summer.

RELATED Kuwait orders death sentence for men accused of spying for Iran

As part of the deal, Tehran will see the release of about $100 billion in Iranian assets in exchange for independent restriction and oversight of the nation's nuclear program.

In 2007, the Revolutionary Guards Navy detained 15 British military personnel for intruding Iran's territorial waters. They were released by Tehran nearly two weeks later.

RELATED Japan to respond strongly to Chinese warships sailing near Senkaku Islands