SEPTEMBER 16, 2009: FBI agents with bomb-sniffing dogs Wednesday raided the Colorado apartment of an Afghan national linked to Al Qaeda and a plot to attack the New York City subway system.... In the past three days, the NYPD increased its attention to the subway system and its 5.2 million daily riders. Officers were warned to keep an eye out for vans near transportation hubs such as Grand Central, police sources said. The safety zone around subway and commuter stations also was expanded by two blocks, the sources said.

Interesting little thought exercise - done in 2004