Cybersecurity is considered as a new sector of homeland security. What threat do cyber-attacks pose to the United States?

Cybersecurity is considered as a new sector of homeland security.
What threat do cyber-attacks pose to the United States?
What if there was a successful terrorist group cyber-attack on the Pentagon, immobilizing the Department of Defense’s network communications or a segment of the U.S. critical infrastructure along the eastern or western coasts? Would this be an act of war? Discuss. Outline the various decisions necessary to mitigate such a disaster.
paper will not be longer than 1 1/2 pages (excluding cover sheet and reference page).