Osama bin Laden and other al Qaeda leaders are believed to be providing strategic and philosophical guidance from Pakistan to Yemen-based al Qaeda in the Arabian Peninsula, or AQAP, the group Washington believes was behind last week’s attempt to ship bombs in packages to the U.S.

Increased communication and collaboration between al Qaeda militants in Yemen and the group’s central leadership have fueled alarm about terrorist plots which U.S. and European officials first detected months ago and which they believe remain active despite efforts to thwart them…

Officials said counterterrorism operations in Pakistan don’t appear to have disrupted the multiple plots, in part because sleeper cells may already be in place in European cities. European authorities have launched an expanded manhunt for individuals who may be involved.