Probably. This isn't entirely unexpected, after what happened with James Foley. This point is only interesting apropos the speculations that several members of ISIL, including Foley's executioner, are British citizens.
Also, I don't see why
the pro-union movement should be anxious. Honestly, popular support still hasn't manifested in a majority for the Scottish issue. Would the Scots actually vote to secede? Surely not. For one, fiscal and economy policy will go down the gutter.