Islamic State claims it could buy its first nuclear weapon from Pakistan within 12 months.
Isis has used its propaganda magazine Dabiq to suggest the group is expanding so rapidly it could buy its first nuclear weapon within a year.
The article, which the group attributes to British hostage John Cantlie, claims Isis has evolved into "the most explosive Islamic movement the modern world has ever seen" in less than 12 months.
Photojournalist Cantlie, who has been held hostage for more than two years, is regularly used in the terrorists' propaganda and has appeared in a number of videos.
The latest article describes militant Islamist groups such as Boko Haram, which recently pledged allegiance to Isis, uniting across the Middle East, Africa and Asia to create one global movement.
"The Islamic State has billions of dollars in the bank, so they call on their wilayah [authority and governance] in Pakistan to purchase a nuclear device through weapons dealers with links to corrupt officials in the region," the article states.
It admits such a scenario is "far-fetched" but warns: "It's the sum of all fears for Western intelligence agencies and it's infinitely more possible today than it was just one year ago. And if not a nuke, what about a few thousand tons of ammonium nitrate explosive? That's easy enough to make."
The capacity of Isis to acquire such a device is certainly beyond the group at the moment but it has secured a number of oilfields in Syria and Iraq.
The finances of the group have been estimated by some to be in the US$2 billion area. The threats come against a mixed backdrop of successes and losses in both countries.
The group has been driven out of Tikrit in Iraq but has overrun Ramaldi and the Syrian ancient city of Palmyra.