Al Qaeda’s leaders yearn to acquire and use weapons of mass destruction against the United States; if they acquired a nuclear bomb, they would not hesitate to use it.
The evidence for those intentions aren’t hidden in encoded communications or classified intelligence. Quite the opposite: They’re hidden in plain sight. Just as Osama bin Laden issued a fatwa to declare war on the United States in 1998, his deputy, Ayman al-Zawahiri, issued a fatwa a decade later to herald a prospective next stage in the conflict. If we take him at his word, some day jihadists will use weapons of mass destruction to change history once and for all.
Of course, al Qaeda leaders have spoken of acquiring weapons of mass destruction for well over a decade. They have had little observable success in achieving their goals of producing a nuclear bomb or biological weapon capable of producing mass casualties. Fortunately, it is extremely difficult, but not impossible, for a terrorist group to acquire a strategic weapon of mass destruction (WMD). Nonetheless, the al Qaeda core has kept at it over the years, in the hopes that time and opportunity will enable it to overcome the daunting challenges in this regard.
What has changed recently is that the goal is no longer theoretical, but operational — a change spurred by Zawahiri’s intervention. Rather than follow bin Laden in issuing a religious edict, Zawahiri chose to release a book in 2008 titled Exoneration. In it, he resurrects a fatwa issued by senior Saudi cleric Nasir al-Fahd in May 2003 — notoriously, the only such treatise that ever endorsed the use of WMD. Zawahiri adopts Fahd’s ideas wholesale. He uses the same ideas, thoughts, examples, and scholarly citations to reach the same conclusion: The use of nuclear weapons would be justified as an act of equal retaliation, “repaying like for like.”
Zawahiri raises key Quranic themes to sweep away all potential objections to the use of WMD. He offers answers to questions about the legality of killing women, children, and the elderly; the justice of environmental destruction; the morality of harming noncombatants; the tactical prudence of attacking at night; and analyses of deterrence. Zawahiri adopts Fahd’s examples verbatim: The Prophet Mohammed’s attack on the village of al-Taif using a catapult, for instance, permits the use of weapons of “general destruction” incapable of distinguishing between innocent civilians and combatants.
http://www.foreignpolicy.com/articles/2010/11/16/al_qaedas_nuclear_ambitions
Terror Trends Bulletin 