The US Government uses simulations of its own vulnerabilities in order to better attack the infrastructure of other nations. This was done in Iraq in 1991, when the US bombed Iraqi infrastructure (the entire electrical system and water treatment installations) with the aim to cause epidemies and death. A UNICEF study reported that this resulted in the deaths of about 500,000 children.
The US Government is widely believed to have also orchestrated the mass murder of 9/11.
The claims that private, amateur terrorists, can inflict serious damage to the US economy, to its computer infrastructure or to its infrastructure, are ludicrous. The only real threat to the US economy would be if most foreign states will stop using the dollar as the main trading currency. This is one of the reasons why Iraq was bombed and why the US is threatening Iran: Both were contemplating to change their oil contracts into Euro.
