Other western governments such as in Canada and the USA also have citizens fighting with militants in Syria and Iraq.
A report in the Mail Online includes footage of Mr Foley prior his death - "'A Message to the U.S.', in which an apparently coerced James Wright Foley, 40, describes America as his true killers for using airstrikes to assist Kurdish forces in recapturing the Mosul Dam from ISIS militants". He is obviously stressed and threatened. Follow this link for the full report and message video.
At time of writing authorities believe the footage of Foley's beheading is genuine.
President Obama now faces tough choices too. He has left Washington again to resume his summer vacation at Martha's Vineyard. Following the "message to America" video IS militants have warned they will kill another journalist unless the US attacks in Iraq cease; American Steven Joel Soltoff is shown in another video. The men all have shaved heads and wear orange suits; this means they resemble prisoners at Guantanamo Bay.
Currently IS could have at least 20 western journalists held captive. Recent airstrikes by US plans have helped tip the balance in Iraq and Kurdish forces regain a vital dam but IS claim that they will respond with more violence.
Syria conflict: President Assad finally turns on Isis as government steps up campaign against militant strongholds