Naval Vessel
© Tim Wimborne / ReutersNaval Vessel
Two small US craft in the Persian Gulf were taken in custody by Iran after they appeared in Iranian waters. The crews are to be released shortly, according to various US officials.

"We have been in contact with Iran and have received assurances that the crew and the vessels will be returned promptly," Pentagon spokesman Peter Cook told AP.

The crews, which total 10 Navy sailors, are being held at Farsi Island, a highly restricted island between Bahrain and Kuwait, where Iran has a naval base. US officials are saying it is unclear how the crew members ended up in Iranian waters, though Secretary of State John Kerry has kept phone contact with Iranian officials in Tehran, urging for a release. A senior official told NBC News the Iranians understand a mistake was made and have agreed to a release to come in hours.

According to AP, an anonymous senior official says Kerry "personally engaged with" Iranian Foreign Minister Javad Zarif to work out a solution almost immediately upon hearing of the development around 12:30 pm EST.

The New York Times reports an anonymous official says the two boats apparently grounded when one of them suffered a mechanical breakdown.
Benjamin J. Rhodes, the deputy national security adviser, gave no details beyond telling The Times, "We are working to resolve the situation such that, obviously, any U.S. personnel are returned to their normal deployment."

Josh Earnest, the White House spokesperson, said the sailors will be released "promptly" and "allowed to continue their journey."

This incident follows recent problematic episodes for the two countries as the US prepares to lift sanctions on Iran as an international agreement to curtail its civilian nuclear program is implemented.

Last week, Russian ships took out 25,000 pounds of low-enriched uranium as part of the nuclear deal.

Last month, the US condemned Iran for conducting tests of its international ballistic missile system in the Straigt of Hormuz, saying the USS Harry S. Truman aircraft carrier and USS Bulkeley destroyer ships were in proximity. On Saturday, the Navy released video of the December 26 test.