From National Review:
On the morning of February 26, 1993, Islamic militants steered a nondescript Ryder van through the winding darkness of the parking garage under the World Trade Center. They had spent years planning this moment in secret meetings at mosques and jailhouses, in rural outposts that served as paramilitary camps, and in safehouses where explosive compounds were mixed in makeshift labs.You can read the whole thing here.
Loaded into the van’s rear compartment was a 1,400-pound chemical bomb.