Al Qaeda in Iraq leader Abu Musab “al-Zarqawi’s agenda was to prove even more radical than that of the al Qaeda leadership; in May [18] 2005, firmly under the al Qaeda banner, al-Zarqawi declared that ‘collateral killing (of Muslims) is justified under dharura [overriding necessity].’ He can also be ‘credited’ with bringing a new level of psychological terror to al Qaeda operations with his ferocious reputation and bloody deeds.”
– Abdel Bari Atwan, The Secret History of al Qaeda, Page 205