Yemen hostage: US reveals bid to rescue Luke Somers
The US has revealed it tried to rescue UK-born American hostage Luke Somers, who is being held by al-Qaeda in Yemen.
President Barack Obama authorised the mission last month, it said.
"Regrettably, Luke was not present, though hostages of other nationalities were present and were rescued," the National Security Council said.
A man identifying himself as Luke Somers, who was abducted in 2013, has appeared in a video, saying his life is in danger and appealing for help.
The video also shows a member of al-Qaeda in the Arab Peninsula (AQAP) threatening to kill Mr Somers unless unspecified demands are met.
Mr Somers, 33, worked as a journalist and photographer for local news organisations and his material appeared on international news outlets, including the BBC news website.
Analysis by Aleem Maqbool, BBC News, Washington
The US saw an opportunity to rescue one of its civilians and took it. But the risk was that failure would put the hostage in further danger. In this video, al-Qaeda in the Arab Peninsula says this is exactly what has happened.
Scrutiny of US policy on dealing with kidnappers has increased with the deaths of three Americans held by Islamic State militants in Syria - each paraded on video, threatened and then beheaded.
The Obama administration has been criticised for not paying ransoms, not allowing hostage families to speak out and not taking opportunities to negotiate.
While the White House stands by its policies, the president has ordered a review.
With its videos and killings, Islamic State has achieved its objectives of spreading fear and gaining notoriety, and this new video from Yemen suggests its propaganda is inspiring other groups.
On 25 November, US and Yemeni forces rescued six Yemenis, a Saudi and an Ethiopian being held by AQAP in an operation at a mountain cave in the remote Hajr al-Sayar district of Hadramawt province. Seven militants were reportedly killed.
US National Security Council spokeswoman Bernadette Meehan said: "As soon as the US government had reliable intelligence and an operational plan, the president authorised the department of defence to conduct an operation to recover Mr Somers."
She added: "The details of the operation remain classified.
"The overriding concern for Mr Somers' safety and the safety of the US forces who undertake these missions made it imperative that we not disclose information related to Mr Somers' captivity and the attempted rescue."
Ms Meehan said the president "could not be prouder" of the US forces who carried out the mission.
"Their effort should serve as another signal to those who would do us harm that the United States will not tolerate the abduction of our people, and will spare no effort to secure the safe return of our citizens and to hold their captors accountable," she said.
AQAP's threat to kill Mr Somers follows the murder of five Western hostages since August by Islamic State, which controls parts of Syria and Iraq.
AQAP is regarded by the US as one of the deadliest offshoots of al-Qaeda.
The group is based in eastern Yemen and has built up support amid the unrest which has beset the impoverished country since the overthrow of President Ali Abdullah Saleh in 2011.