Descriptions of the alleged plot uncovered by British authorities have distinct echoes of the so-called Operation Bojinka, an attempt by supporters of al Qaeda in the mid-1990s to simultaneously destroy airliners over the Pacific using liquid explosives. The explosives, which can be hidden in a small bottle, like those used for contact lens solution, are hard to detect, and were originally developed by Yousef, whose uncle, Mohammed, was the chief architect of the 9/11 attacks. In December 1994, Yousef tested his device using a fraction of the explosives planned for the main bombs. Halfway through the short flight, Yousef disappeared...