Perhaps such a test might come in the form of EMP devices: Electro Magnetic Pulse devices or bombs.
Such devices can render all electronic devices, and thus communications, in the blast radius inoperable. Think about it: if people aren't able to use their mobile phones, television or internet connections to receive news of what is happening, they are completely disconnected from other parts of the city/state/country/world. Also, if such EMP devices are set off at water plantations or power stations, the entire area would be without electricity or water supply. How quickly will this bring t