Air Force One with U.S. President Bill Clinton and first lady Hillary Clinton aboard was on its final approach to Manila on Nov. 23, 1996, when their U.S. Secret Service detail received alarming intelligence: An explosive device had been planted on the motorcade route into the Philippines capital.

Acting swiftly, the agents switched to a back-up route to the Clintons' hotel, foiling a suspected al-Qaida attempt to assassinate the president of the United States minutes after his arrival for the annual Asia-Pacific Economic Cooperation summit.

As the motorcade crawled along the traffic-clogged alternate route, Filipino security officers recovered a powerful bomb on a bridge the convoy would have taken and an SUV abandoned nearby containing AK-47 assault rifles, four retired agents said.