For critical systems and data, the restoration process must be tested.

"Is this thing attached to any of the building's critical systems?"

And various systems, so far none critical, were breaking down.

Especially when so many more critical systems were also in the midst of overhaul.

Other critical systems, such as telecommunications, are also required to have emergency power.

Brakes are one of the most critical systems on a car.

It also has its own on-board computer system to watch over critical systems.

But the critical systems, which is to say me talking to you, just went through without batting an eye.

"Intentional attacks against our critical systems are already under way," he said.

Thus, critical systems are very sensitive to small changes in the environment.