US aid worker Peter Kassig may be Islamic State militants' next target
Fears grow for US aid worker Peter Kassig's safety after he appears in video showing extremist group's beheading of British hostage
The family of an American humanitarian worker being held captive by Islamic State militants have made a desperate plea for their son's release as fears grow he has been earmarked as the extremist group's fifth victim.
Peter Kassig appeared in the online video on Friday that showed the beheading of British hostage Alan Henning, after which a masked militant threatens to behead the Iraq war veteran next.
The group is now being targeted in United States-led air strikes.
In a three-minute video posted on YouTube, Kassig's father, Ed, says: "We implore his captors to show mercy and use their power to let our son go."
His mother, Paula, says: "Please know that we are all praying for you and your safe return. Most of all, know that we love you."
The killing of Henning, a 47-year-old taxi driver who went to the region as a volunteer to deliver aid, sparked an outcry.
Britain's Prime Minister David Cameron said Henning was a "man of great peace, kindness and gentleness", adding: "The fact they could murder him in the way they did shows what we are dealing with."
Henning's family said they were "numb with grief" over the murder of a "decent, caring" man. His wife, Barbara, and his two children said they had hoped never to receive news of his killing.
"Alan was a decent, caring human being. His interest was in the welfare of others. He will be remembered for this and we as a family are extremely proud of him and what he achieved and the people he helped," they said.
Henning's brother-in-law, Colin Livesey, told BBC television the British government could have done more to protect him.
"They could have done more when they knew about it months and months ago. I just don't think they did enough in my eyes."
The video showing Kassig was released in the same manner as other Islamic State beheading videos, and the masked militant sounded similar to the one seen in the previous videos. The group had previously executed American reporter James Foley, American-Israeli journalist Steven Sotloff and British aid worker David Haines.
US National Security Council spokeswoman Caitlin Hayden confirmed that Kassig was being held by Islamic State militants. "We will continue to use every tool at our disposal - military, diplomatic, law enforcement and intelligence - to try to bring Peter home to his family," she said.
According to his parents, Kassig, who is from the city of Indianapolis, converted to Islam while in captivity and now goes by the name Abdul-Rahman.
In an interview with last year, Kassig said he travelled a lot throughout Lebanon to assess the needs of the people there.
He said he designed his organisation, Special Emergency Response and Assistance, around the belief that "there was a lot of room for improvement in how humanitarian organisations interact with and cooperate with the populations they serve".
"It's about showing people that we care, that someone is looking out for those who might be overlooked," he said.
Last week, a US marine became the first American to be killed in the air campaign against Islamic State militants. Corporal Jordan Spears, 21, bailed out of his Osprey helicopter after it lost power.
Pakistani Taliban pledge allegiance to Islamic State
The Pakistani Taliban last night declared allegiance to the Islamic State group and ordered militants across the region to help the Middle Eastern jihadist group in its campaign to set up a global caliphate.
Islamic State, which controls large areas in Syria and Iraq, has been making inroads into South Asia, which has traditionally been dominated by local Taliban insurgencies against the governments of both Pakistan and Afghanistan.
The announcement comes after a move last month by al-Qaeda chief Ayman al-Zawahiri to name former Taliban commander Asim Umar as the "emir" of a new South Asia branch of the network that masterminded the 2001 attacks on the United States.
Although there is little evidence of a firm alliance yet between Islamic State and al-Qaeda-linked Taliban commanders, Islamic State activists have been spotted in Peshawar distributing pamphlets.
IS flags have also been seen at street rallies in Indian-administered Kashmir. The trend has been of growing concern to global powers struggling to keep up with the fast-changing nature of the international Islamist insurgency.
In a message marking the Muslim holy festival of Eid ul-Adha, the Pakistani Taliban said they fully supported IS goals.
"Oh our brothers, we are proud of you in your victories. We are with you in your happiness and your sorrow," Taliban spokesman Shahidullah Shahid said in a statement sent to Reuters by email from an unknown location.
"In these troubled days, we call for your patience and stability, especially now that all your enemies are united against you. Please put all your rivalries behind you …
"All Muslims in the world have great expectations of you … We are with you, we will provide you with mujahideen [fighters] and with every possible support."
The statement came despite recent speculation that the Taliban leadership, whose goal is to topple the government and set up a sharia state, is actually wary of IS, which is driven by different ambitions that have little to do with South Asia.
