A stark warning has been been issued that dissident republican terrorists are "desperate for a kill" in targeting police officers.
The dire assessment by a security source, who wished to remain anonymous due to concerns for their own safety, comes as Northern Ireland's terror threat level was raised from substantial to severe on Tuesday.
MI5 increased the threat to Northern Ireland from Northern Ireland Related Terrorism from "Substantial" (an attack is likely) to "Severe" (an attack is highly likely) on Tuesday.
