The overarching question imparting urgency to this exploration is: Can U.S.-Russian contention in cyberspace cause the two nuclear superpowers to stumble into war? In considering this question we were constantly reminded of recent comments by a prominent U.S. arms control expert: At least as dangerous as the risk of an actual cyberattack, he observed, is cyber operations’ “blurring of the line between peace and war.” Or, as Nye wrote, “in the cyber realm, the difference between a weapon and a non-weapon may come down to a single line of code, or simply the intent of a computer program’s user.”
Why do nations break into one another's most important computer networks? There is an obvious answer: to steal valuable information or to attack. But this isn't the full story. This book draws on often-overlooked documents leaked by Edward Snowden, real-world case studies of cyber operations, and policymaker perspectives to show that intruding into other countries' networks has enormous defensive value as well. Two nations, neither of which seeks to harm the other but neither of which trusts the other, will often find it prudent to penetrate each other's systems. This general problem, in which a nation's means of security itself threatens the security of others and risks escalating tension, is a bedrock concept in international relations and is called the 'security dilemma'.