Last Updated Jan 12, 2016 5:59 PM EST
WASHINGTON -- The Pentagon says it briefly lost contact with two small Navy craft in the Persian Gulf on Tuesday but has received assurances from Iran that the crew and vessels will be returned safely and promptly.
Pentagon spokesman Peter Cook told The Associated Press that the riverine boats were moving between Kuwait and Bahrain when the U.S. lost contact with them.
A Defense Department official told CBS News Pentagon correspondent David Martin it appears the two boats came within 12 miles of Farsi Island, which is held by Iran.
Officials told the AP the incident stemmed from some type of mechanical trouble with one of the boats, causing them to run aground.
Martin reported the boats had about 10 crew members on board and that Iran has assured the U.S. the sailors were being treated well and would be allowed to continue on their journey once it is daylight.
"We have been in contact with Iran and have received assurances that the crew and the vessels will be returned promptly," Cook said.
The U.S. 5th Fleet is based in Bahrain, which is a major hub of U.S Navy operations, Martin said.
Secretary of State John Kerry, who has forged a personal relationship with Iranian Foreign Minister Mohammed Javad Zarif through three years of nuclear negotiations, called Zarif immediately on learning of the incident, according to a senior U.S. official.
Kerry "personally engaged with Zarif on this issue to try to get to this outcome," the official said.
Kerry learned of the incident around 12:30 p.m. EST as he and Defense Secretary Ash Carter were meeting their Filipino counterparts at the State Department, the official said.
President Obama has been briefed on the incident, a senior administration official told CBS News.
Martin pointed out this would seem a harmless incident except that two weeks ago, Iranian Revolutionary Guard ships fired off rockets within a mile of the American aircraft carrier U.S.S Truman.
The rockets were aimed the other way, but firing live munitions in the middle of crowded shipping lanes drew a strong protest from the U.S.
The officials were not authorized to discuss the sensitive incident publicly so spoke on condition of anonymity.