Why was David Haines killed?

David Haines was killed by ISIS in September 2014 because he was a British aid worker who had been captured while working in Syria. His execution was part of a broader campaign by ISIS to instill fear and gain attention for their activities, particularly targeting Western nations involved in military actions against them. Haines's death was publicly framed by ISIS as retaliation for the UK’s involvement in airstrikes against the group. His killing highlighted the peril faced by humanitarian workers in conflict zones.