Families of British servicemen are being told to stop sharing personal details online after Islamic extremists sent a chilling death threat to a soldier's home.
The note entitled "Jihad: The Holy War of Islam" warns servicemen and "brides of British Soldier Warmongers" that they will "pay the price" for destruction in "the Holy Land".
Police are investigating the letter which was thought to have been posted through an address in Skegness, Lincolnshire -- with the family thought to have fled their home.
Chief Inspector Jim Tyner, of Lincolnshire Police, said he believes that this is a one-off incident, says The Mirror.
"Lincolnshire Police are investigating an allegation of malicious communications where a threatening letter has been sent to the home of a serving member of the armed forces," he said.
"At present we believe this is a one off-incident and would like to hear from any families that had received similar letters.
"We would like to remind forces families of the need to take particular care. For example, they should review their security settings on social media to ensure they don't accidentally share personal details."
The letter which is signed off "The Circle of Allah – Avengers Serving Allah" was made in Lincolnshire, which has nine armed forces bases.
An MoD spokeswoman added: "Keeping personnel and their families safe is of the utmost importance and all personnel are given clear guidance on appropriate social media use.
"We do not talk about specific security measures."
In November last year Police officers were warned not to wear their uniforms while travelling to and from work over fears they could be targeted in a terrorist attack.
The letter echoes the murder of Fusilier Lee Rigby who was murdered in Woolwich in southeast London in 2013 by Michael Adebolajo and Michael Adebowale.
They were jailed for life and 45 years respectively after a trial in December 2014.