Some people project their fears onto others. They believe that if we are aggressive enough, and attack the "other", we will be safe.
But security does not come from violence. Indeed, all of the people and empires that have tried to defend themselves by attacking others fell in a dramatic fashion. The saying "those who live by the sword shall die by the sword" comes from the simple fact that violence cannot provide lasting security.
Instead, real security comes from cooperation, justice, dignity and freedom. When there is cooperation, and when people enjoy justice, dignity and freedom, they are not motivated to commit violence on others. That brings real security.