Terrorism (or guerrilla warfare if you prefer) depends on surprise attacks so if an attack is imminent there is silence.
After and attack they are many false alarms, this is to cause confusion and to give their allies in media (Dan et al) and government (hillary et al) ammunition against the target country (USA).
the terrorists are smarter than the voters and media consumers
Doesn't anyone else get tired of so many freepers missing the point? We're at war with Al Qaeda, not our own two party system. Yes, we live in a nation populated with liberals, moderates and conservatives--but let's not think for one minute that we have a war between just the American conservatives and Al Qaeda.
And yes, Al Qaeda would love to drive a wedge to divide Americans on the war effort, but let's not help them.