Should the need arise, Islamic State (formerly ISIS/ISIL) could buy a nuclear weapon in Pakistan within 12 months, the group's in-house magazine boasts in an article attributed to hostage journalist John Cantlie.

The article talks about a "hypothetical operation" in which the Islamic State uses its "billions of dollars" to buy a nuclear device in Pakistan "through weapons dealers with links to corrupt officials in the region."

The weapon could then be transported through Libya and Nigeria. The article suggests that "drug shipments from Columbia bound for Europe pass through West Africa, so moving other types of contraband from East to West is just as possible."

The device would land on the south shores of South America and make its way to Mexico, from where "it’s just a quick hop through a smuggling tunnel" to the US. The chilling conclusion is that in the end, "they’re mingling with another 12 million 'illegal' aliens in America with a nuclear bomb in the trunk of their car."

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The author admits this is a "far-fetched" scenario, but goes on to say it is far more possible now than it was a year ago.

Islamic State, he says, "will be looking to do something big, something that would make any past operation look like a squirrel shoot." Something of the scale could be made possible, according to the article, by an unprecedented condensation of various extreme Islamist groups under the terror organization’s wing.

The article mentions militant groups such as Boko Haram, which recently pledged allegiance to Islamic State. It says there are many Boko followers across the Middle East given confidence by the territorial gains made by the ISIS terrorists: "Nothing on this scale has happened this big or this quick before. Huge swathes of Pakistan, Nigeria, Libya, Yemen and the Sinai Peninsula are all now united under the black flag."

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The estimates as to the number of ISIS fighters across the territories it control vary greatly. The total number in Iraq and Syria range from about 30,000, according to CIA estimates, to up to 70,000 according to the Russian military, to as many as 200,000, according to a November statement by a Kurdish leader.

It is even more difficult to pinpoint the exact amount of money Islamic State has in its disposal. Some estimates have suggested it has about $2 billion in assets, which puts buying a nuclear weapon far beyond its capability at the moment.

Photojournalist John Cantlie, who is named in the magazine as the author of the article, is a hostage of the Islamic State. The terrorists have held him for over two years now, and used him in a number of propaganda videos. In those videos he says he has converted to the Islamic State’s extremist ideology, but it is widely believed he is being intimidated into making such statements.