Does cyberspace favor the offense, as many analysts and policymakers claim? Three factors undermine any cyber offensive advantage, as demonstrated in a cost-benefit analysis of the Stuxnet operation against Iran. First, any measurement of the offense-defense balance must consider a cyber operation’s value as well as its cost to both sides. Second, organizational capabilities play a significant role in determining the balance. Third, offensive advantages decline when attackers target physical infrastructure rather than information networks.