We read today that insurgents in Iraq somehow got into the heavily fortified Green Zone and set off a bomb, killing two Iraqi parliamentarians. In addition, another bomb was set off on a major bridge north of Baghdad, destroying the bridge and sending several cars plunging into the Tigris.
These are a couple of examples of how 4th Generation Warfare can be effective at destroying systems - both of governance and infrastructure. John Robb calls this type of emphasis the systempunkt (a play off the German Blitzkrieg concept of schwerpunkt).
To recap, modern complex communications, utility and transportation systems are vulnerable to attack, throwing a potentially thriving community into chaos. These attacks may be performed by small groups or individuals who have a grudge. These groups don't have to attack heavily armed troops or police to get their point across - they can do immense damage just by attacking the infrastructure that support those troops and the community at large.
Now, combine this ability, which has been shown time and time again in the laboratory of Iraq, with the coming wave of negative mood that will be sweeping the U.S. (Note - this assumption of mine will be delayed if you see the DJIA cross 12,900) which has been shown to lead to anger, violence and a tendency to want to break things apart rather than build them up.
If you see DJIA 6,000 - the bridge you read about being blown up may just be one over the Mississippi River instead of the Tigris.
Here's hoping this rally still has legs and that we can spend that time preparing for the coming storm.