…cyberwarfare is asymmetric. The low cost of computing devices means that U.S. adversaries do not have to build expensive weapons, such as stealth fighters or aircraft carriers, to pose a significant threat to U.S. military capabilities. A dozen determined computer programmers can, if they find a vulnerability to exploit, threaten the United States' global logistics network, steal its operational plans, blind its intelligence capabilities, or hinder its ability to deliver weapons on target. Knowing this, many militaries are developing offensive capabilities in cyberspace, and more than 100 foreign intelligence organizations are trying to break into U.S. networks. Some governments already have the capacity to disrupt elements of the U.S. information infrastructure.
In cyberspace, the offense has the upper hand. The Internet was designed to be collaborative and rapidly expandable and to have low barriers to technological innovation; security and identity management were lower priorities. For these structural reasons, the U.S. government's ability to defend its networks always lags behind its adversaries' ability to exploit U.S. networks' weaknesses. Adept programmers will find vulnerabilities and overcome security measures put in place to prevent intrusions. In an offense-dominant environment, a fortress mentality will not work. The United States cannot retreat behind a Maginot Line of firewalls or it will risk being overrun. Cyberwarfare is like maneuver warfare, in that speed and agility matter most. To stay ahead of its pursuers, the United States must constantly adjust and improve its defenses.
It must also recognize that traditional Cold War deterrence models of assured retaliation do not apply to cyberspace, where it is difficult and time consuming to identify an attack's perpetrator. Whereas a missile comes with a return address, a computer virus generally does not. The forensic work necessary to identify an attacker may take months, if identification is possible at all. And even when the attacker is identified, if it is a nonstate actor, such as a terrorist group, it may have no assets against which the United States can retaliate. Furthermore, what constitutes an attack is not always clear. In fact, many of today's intrusions are closer to espionage than to acts of war. The deterrence equation is further muddled by the fact that cyberattacks often originate from co-opted servers in neutral countries and that responses to them could have unintended consequences.