An article in today’s NYTimes about cyber crime, malware, etc. suggests to me that another line of attack may be through the Internet against our utilities, telecoms, or financial institutions.
There have already been massive attacks against whole countries with successful breakdowns that lasted for hours and days. Ukraine, Lithuania, and Georgia were targets over the last year. My memory is that suspicions fell to the Russian government because the attacks, in these cases massive Denial of Service assaults, appeared to originate from within Russia.
At any rate, add this to your terror worries.