Al Qaeda has yet to follow its spectacular 9/11 attacks in the United States with anything nearly as dramatic or effective. Why? The once-centralized terrorist group is becoming more amorphous. Al Qaeda leader Osama bin Laden was killed at his safe-house in Abbottabad, Pakistan, May 2, 2011, by U.S. special operations forces. Yet the likelihood of another big attack could increase as memories of 9/11 fade and as jihadists hone their skills in Iraq and Afghanistan.
