From the New York Post, :
May 31, 2004 — An internal NYPD memo warns that terrorists are seeking truck-driver licenses to try to use the vehicles as mobile bombs, Sen. Charles Schumer said yesterday.
Schumer (D-N.Y.) said the memo, recently sent to the Office of Emergency Management, highlights the need to tighten security on the millions of trucks that enter the city every year.
“The worst-case scenario is something like Oklahoma City,” Schumer said.
The first attack on the World Trade Center in 1993 also made use of a truck bomb.
The memo comes amid federal alerts that al Qaeda operatives may be planning an attack on New York this summer – and an FBI warning that terrorists may use trucks to target city icons such as the Empire State Building.