Bojinka

As soon as Yousef arrived in Manila along with other so-called "Arab Afghans" that were making cells in Manila, he started to work on making bombs. Yousef had shown up in Singapore with Khan earlier in fall 1994. The two got their Philippine visas in Singapore.

His first operational test of his bomb was inside a mall in Cebu City. The bomb detonated several hours after Yousef put it in a generator room. It caused minor damage, but it proved to Yousef that his bomb was workable.

He left Manila for several days, but was met by Islamist emissaries upon his return to Metro Manila. They asked him to attack United States President Bill Clinton, who was due to arrive in the Philippines on November 12, 1994 as part of a five-day tour of Asia. Yousef thought of several ways to kill the president, including placing a bomb on Clinton's motorcade route, firing a Stinger missile at Air Force One or the presidential limousine, and killing him with phosgene, a chemical weapon. He abandoned the idea, as it would be too difficult to kill the President. However, he incorporated his plan to kill the Pope into the Bojinka plot.

In 1994, Yousef and Khalid Sheik Mohammed started testing airport security. Yousef booked a flight between Kai Tak International Airport in Hong Kong and Taiwan Taoyuan International Airport near Taipei. Mohammed booked a flight between Ninoy Aquino International Airport near Manila and Kimpo International Airport near Seoul.

The two had already converted fourteen bottles of contact lens solution into bottles containing nitroglycerin, which was readily available in the Philippines. Yousef had taped to the arch of his foot a metal rod, which would serve as a detonator. The two wore jewelry and clothing with metal to confuse airport security. To support their claim that they were meeting women, they packed condoms in their bags.[4]

On December 8, Yousef moved into