10 US navy soldiers held by Iranian forces
Iran is holding 10 US navy sailors and their two small boats after the vessels developed mechanical problems and drifted into Iranian waters, US officials have confirmed.
The Pentagon said it had received assurances from Tehran that the sailors and their boats will be returned safely and promptly.
Pentagon spokesman Peter Cook said the riverine boats were moving between Kuwait and Bahrain when the US lost contact with them.
American officials said the incident happened near Farsi Island in the Persian Gulf.
They said that some type of mechanical trouble caused them to run aground, where they were picked up by Iran.
The sailors were in Iranian custody on Farsi Island at least for some time, but it is not certain where they are now.
The semi-official Iranian news agency, FARS, said the Iranian Revolutionary Guard's navy had detained 10 foreign forces, believed to be Americans, and that the sailors were trespassing in Iranian waters.
Mr Cook said: "We have been in contact with Iran and have received assurances that the crew and the vessels will be returned promptly."
The incident comes amid heightened tensions with Iran, and only hours before president Barack Obama is set to deliver his final State of the Union address to Congress and the public.
It set off a dramatic series of calls and meetings as US officials tried to determine the exact status of the crew and reach out to Iranian leaders.
US 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 Mr Zarif immediately on learning of the incident, according to a senior US official.
Mr Kerry "personally engaged with Zarif on this issue to try to get to this outcome," the official said.
Mr Kerry learned of the incident as he and Defence Secretary Ash Carter were meeting their Filipino counterparts at the State Department.
This comes on the heels of an incident in late December when Iran launched a rocket test near US warships and boats passing through the Strait of Hormuz.
Iran is expected to satisfy the terms of last summer's nuclear deal in a matter of days.
Once the UN nuclear agency confirms Iran's actions to roll back its programme, the United States and other Western powers are obliged to suspend wide-ranging oil, trade and financial sanctions on Tehran.
Mr Kerry recently said the deal's implementation was "days away".