Kennedy describes a cycle in which fear and mistrust between rival states reinforce one another. When one side interprets the other as threatening, it may strengthen its military position for protection. The opposing side can then view those measures as evidence of hostile intent and respond with further preparations of its own.

In the context of the Cold War, Kennedy applies this logic to the nuclear arms race between the United States and the Soviet Union. Each new weapon could prompt a corresponding development by the other side, increasing both expenditure and the risks of escalation. The quotation closely reflects what is often described as a security dilemma: actions intended to make one state safer can make its rival feel less secure, producing a cycle that leaves both worse off. Kennedy uses the argument to support efforts to reduce suspicion, improve communication and limit uncontrolled military competition.