A decade after he disappeared, the US government has said that they are certain American journalist Austin Tice is being held by the Syrian government.
In a statement to mark ten years since Tice disappeared, US President Joe Biden said: "We know with certainty that he has been held by the government of Syria."
"We have repeatedly asked the government of Syria to work with us so that we can bring Austin home. On the tenth anniversary of his abduction, I am calling on Syria to end this and help us bring him home."
"There is no higher priority in my administration than the recovery and return of Americans held hostage or wrongfully detained abroad."
Tice disappeared at a checkpoint in a government-controlled area west of Damascus on 14 August 2012 after going to Syria to cover the fighting.
A month after he was kidnapped, Tice appeared in a video, blindfolded, with armed men. The video was published on a Facebook page of supporters of Syrian President Bashar Al-Assad, reports CBS News.
This footage is the last time Tice has been seen alive. If he is still being held captive by Syria, he is the longest-held American journalist of all time.
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Tice's mother told CBS News: "There is no reason not to believe that he's waiting and hoping and dreaming and planning to walk free."
Debra Tice called on the US government to do more to bring her son home. "The United States government has worked very hard to convince me that they're working on it. My response is: Don't tell me. Show me."
Despite travelling to Syria two years ago to negotiate Tice's release, the US government failed to do so, with Syrian officials never admitting holding him.
The US has 900 troops in the northeast of Syria and has periodically carried out air strikes as part of its fight against Daesh.
The Syrian government has said it will not discuss hostages with the US whilst US troops remain in the country.
February marked five years since the disappearance of another US hostage Majd Kamalmaz from Syria.
Kamalmaz is a psychologist who treated patients in the region traumatised by the Syrian war and was in Syria visiting his family when he was stopped by the Syrian regime.