A Masked Islamic State Militant Holding A Knife Speaks Next To Man Purported To Be U.S. Journalist James Foley At An Unknown Location In This Still Image From An Undated Video Posted On A Social Media Website
A masked Islamic State militant holding a knife speaks next to man purported to be U.S. journalist James Foley at an unknown location in this still image from an undated video posted on a social media website. REUTERS/Social Media Website v

King ­Abdullah of Saudi Arabia warned authorities in both Europe and the United States to be extra vigilant as members of the ISIS terror group could already be in their respective countries, preparing to unleash terrifying atrocities in the next two months at least.

This, as a computer laptop seized in northern Syria by pro-Western rebels from a Tunisian jihadi revealed plans to develop and use biological weapons.

Theresa May, UK's Home Secretary, said intelligence reports have yet to suggest an imminent attack on the country, but authorities nonetheless have raised its terror threat level from "substantial" to "severe" to warn citizens that a terrorist attack is "highly likely."

Abdullah warned both superpowers that terrorism "knows no border and its danger could affect several countries outside the Middle East."

British Prime Minister David Cameron seconded the Saudi King's words, noting what the militant group did to American journalist James Foley can also be done right under their noses in their very own homeland. This is something we simply cannot hope to ignore, he said.

If neglected, King ­Abdullah said the ISIS will attack Europe after a month and the U.S., the following month.

He warned the children in those Western regions do not stand a chance. "You see how they [jihadists] carry out beheadings and make children show the severed heads in the street."

Either those beheadings, or they be able to wipe out massive human casualties using biological weapons.

Foreign Policy, which was given access to a computer laptop that was seized in a raid in January in the Syrian province of Idlib, near the Turkish border, reported seeing thousands of files of schemes, bomb-making instructions and research on building a homebrew biological weapon of mass destruction.

Foreign Policy described the contents as "a treasure trove of documents that provide ideological justifications for jihadi organisations -- and practical training on how to carry out the Islamic State's deadly campaigns."

One such document was done in 19 pages in Arabic language where the topic was how to develop biological weapons and how to use as a weapon the bubonic plague from infected animals.

The document owner was identified as Muhammed S., a Tunisian national who was a former chemistry and biology student at a Tunisian University.

He reportedly wrote in the document that while creating biological weapons do not cost a lot of money, its resulting effects are far worthy because "human casualties can be huge."

Foreign Policy called the Tunisian university where Muhammed last attended school. A female staff member confirmed he studied chemistry and physics there, but that it was 2011 when he was last seen there.

Foreign Policy was surprised when the staff member asked them if they found Muhammed's papers inside Syria. When asked what made her think that, her reply was short but loaded, "For further questions about him, you better ask state security."

Muhammed made instructions how to test the disease safely, before launching it in a terrorist attack. "When the microbe is injected in small mice, the symptoms of the disease should start to appear within 24 hours," the document said.

How best to use the biological weapon? By disposing them in closed areas. "Use small grenades with the virus, and throw them in closed areas like metros, soccer stadiums, or entertainment centers," the file said.

"Best to do it next to the air-conditioning. It also can be used during suicide operations."

A 26-page fatwa, or Islamic ruling, on the usage of weapons of mass destruction was likewise found among the files. "If Muslims cannot defeat the kafir [unbelievers] in a different way, it is permissible to use weapons of mass destruction," states the fatwa by Saudi jihadi cleric Nasir al-Fahd, who is currently imprisoned in Saudi Arabia. "Even if it kills all of them and wipes them and their descendants off the face of the Earth."

It is unknown if the jihadists have already created or possess the chemical or biological weapons.