Extensive and widespread dependence on the Internet has called new attention to the importance of information to national security. The term information warfare refers to the act of war against the information resources of an adversary. Like warfare on land or in the air, information warfare is one component of a range of attack strategies for dominating an adversary in order to gain or maintain an objective. Information warfare is divided into two categories: offensive and defensive. The purpose of offensive information warfare is to attack the information resources of an adversary to gain dominance. Defensive information warfare is the protection of your information assets against attack. Information assets can take many forms, from messages sent by courier in diplomatic bags to the computers used to analyze enemy positions based on satellite data. In computer security, information assets include digital information, the computers that process them, and the networks that transmit the digital information from place to place. Computer security is a key element for protecting the availability, integrity, and confidentiality of all these information assets. Internet security protects information assets consisting of computers, information, and networks that are part of the Internet. Internet security is related to information warfare when the Internet contains information assets that are important to the information warfare objective. For example, if an adversary can use the Internet to access battle plans, the Internet is being used for information warfare. Internet security is important to both offensive and defensive information warfare because the Internet is a global and dependable resource on which many countries rely. Historically, military networks and computers were unreachable by nonmilitary participants. The Internet, however, provides a cost-effective way for military and government units to communicate and participate in achieving objectives. Use of the Internet means that individuals, multinational companies, and terrorist organizations all can gain access to important information resources of governments and military forces. Thus, it is important to address Internet security concerns as a key component of defensive information warfare. Because the Internet is global, it can be an avenue of attack for offensive information warfare by many governments. One of the battlefields for a future military offensive could very well involve the Internet. Intruder technology (as described in a separate section above) could be used by a government as a weapon against information resources, or used randomly by a terrorist organization against civilian targets. In the study of information warfare, there are many new problems to solve that are not evident in other forms of warfare. These problems include identifying the enemy, responding without making your systems vulnerable to attack, and gathering intelligence on the Internet about preparations for a military exercise. These and other problems are likely to be the subject of discussion and investigation for some time to come.