American journalist Theo Curtis has been released after being kidnapped in Syria two years ago, US Secretary of State John Kerry said on Sunday.
Mr Kerry said in a statement that the United States was using"every diplomatic, intelligence and military tool" at its disposal to secure the release of other Americans held hostage in Syria.
The news of Mr Curtis' release came just days after what Mr Kerry called "unspeakable tragedy" after Islamic State militants killed American journalist James Foley, who was kidnapped in Syria in 2012
British authorities earlier said they are "close" to identifying the hooded Islamic State jihadist who beheaded Mr Foley, the British ambassador to the United States said Sunday.
"I can't say more than this but I know from my colleagues at home that we are close," British Ambassador to the US Peter Westmacott said.
The Sunday Times newspaper, citing unnamed senior government sources, reported that intelligence services MI5 and MI6 have identified the fighter suspected of killing Mr Foley but the sources did not divulge the suspect's name.
The jihadist, who was shown on video executing Mr Foley and then threatening to kill a second US hostage if President Barack Obama did not change course in Iraq, spoke English with a British accent.
"We're putting a lot into it and there are sophisticated technologies, voice identification and so on which people can use to check who these people are," Mr Westmacott said.
He said as many as 500 British subjects have gone to Syria and Iraq to fight for the jihadist movement.
British Foreign Secretary Philip Hammond said in an article published by the Times of London that Mr Foley's killing was an "utter betrayal of our country."
"It is horrifying to think that the perpetrator of this heinous act could have been brought up in Britain," Mr Hammond wrote.