The bombing of the Boston Marathon by two young Chechen immigrants to the United States and the damage on April 16 to several transformers at the critical PG&E Metcalf Road substation that serves Silicon Valley should remind us that attacking critical infrastructure by cyber means isn't the only way to injure the U.S. economy by terror.
In fact, the threat scenarios that truly frighten the anti-terrorism folks in federal, state and local governments include multiple attack vectors and wave attacks.