Preventing war in space is of the utmost importance because of the lasting effects such a war would have. Deterrence by denial is difficult for the four types of attacks against space assets kinetic, non-kinetic physical, electromagnetic, and cyber. However, deterrence by punishment, specifically through horizontal escalation, is viable for kinetic attacks. International norms and a deterrence policy for kinetic attacks need to be developed. Additional effort is necessary to mature attribution and defense capabilities for the other types of attack and, possibly, to extend the theory and practice of deterrence to these types of attacks.