AYMAN AL-ZAWAHIRI, the second-in-command of Osama bin Laden, has delivered a video statement, broadcast by al Jazeera, threatening more terror by al Qaeda in Britain and in the United States. His rant must be taken extremely seriously.

First, while Osama bin Laden is a hateful, murderous Islamist radical, there is a difference in psychology between him and Zawahiri. Bin Laden falls into the category of those who became radicals to fill a void in their lives. The scion of a colossally rich family, bin Laden is said to have first arrived at the jihadist frontlines in Pakistan, decades ago, with the typical dress and manner of a cosmopolitan Saudi. His radicalism springs from resentment that the Saudi kingdom has strayed from the path of pure Wahhabism, the state religion.