Islamic State militants have beheaded another American hostage, Peter Kassig, issuing a video claiming the killing yesterday and warning the US they would kill other US citizens "on your streets."

The parents of a US aid worker threatened with beheading by the Islamic State group say they have broken their silence about their son’s year-long captivity because "the dynamics have changed" and they fear for his life.

The parents of a US aid worker held captive by the Islamic State group have revealed he told them in a letter he was afraid to die, but that he had converted to Islam voluntarily and was at peace with his beliefs.