Isis, the self-proclaimed Islamic State, has called for lone wolf attacks in the UK in retaliation for the recent British intervention in Iraq.
The Sunni insurgent group, which has seized large parts of Iraq and Syria, has called on Islamic fighters across the world to take on the "infidels".
Its call comes in the latest edition of the English-language magazine Dabiq.
"At this point of the crusade against the Islamic State, it is very important that attacks take place in every country that has entered into the alliance against the Islamic State, especially the US, [the] UK, France, Australia and Germany," the extremist organisation said.
"The citizens of crusader nations should be targeted wherever they can be found."
Britain recently stepped up its participation in the US-led military campaign against Isis in Iraq. A "small specialist team" of 12 military personnel has also been sent to the Kurdish capital of Erbil to train the Peshmerga forces against the militants.
The UK police have also warned of emerging threats saying any officer could be targeted.
An article in the fourth edition of Dabiq, which has become another Isis propaganda tool, urges Muslims not to think too much before taking on the "enemies" since it would lead to "analysis paralysis".
"Every Muslim should get out of his house, find a crusader and kill him ... Secrecy should be followed when planning and executing any attack. The smaller the numbers of those involved and the less the discussion beforehand, the more likely it will be carried out without problems."
"One should not complicate the attacks by involving other parties, purchasing complex materials, or communicating with weak-hearted individuals."