The 10 U.S. sailors briefly held by Iran before being released on Wednesday made a navigational mistake that led them into Iranian waters but did not communicate that to Navy commanders before being intercepted, the U.S. military said on Thursday.
U.S. Defense Secretary Ash Carter said the information came from debriefings of the sailors, who were flown on Wednesday to a U.S. military facility in Qatar after Iran released them along with their two riverine boats.
"The information that they have given us, and through their commanders, is that they did stray accidentally into Iranian waters due to a navigation error," Carter said in an interview with FUSION television's Jorge Ramos, which will also air on Spanish-language Univision.
Carter's comments were the most detailed so far from American officials on the incident, which rattled nerves just before the expected implementation of a landmark nuclear deal between Iran and world powers.
Diplomats in Washington and Tehran, through a series of anxious phone calls, sought to resolve the incident quickly, ensuring it did not torpedo the nuclear accord.
In the end, Iran released the U.S. sailors - nine men and one woman - on Wednesday, a day after they were detained.
The speedy resolution of the incident contrasted with previous cases in which British servicemen were held considerably longer, in one case nearly two weeks.