Understanding how changes to war-fighting technology influence the probability of war is central to security studies. Yet the effects of changes in the distribution of power are not obvious. All else equal, increasing a country’s power makes it more aggressive when making demands or more resistant to accepting offers, but all else is not equal. Changes in power influence the behavior of both countries and can generate countervailing incentives. In this note we characterize the conditions relating changes in war payoffs to changes in the probability of bargaining failure and war. For a variety of cases the strategic effects can be entirely offsetting and no change in the probability of war results from changes in the balance of power, a result sometimes called neutrality. When this neutralization does not occur, interesting and sometimes surprising effects can persist. For example, if countries are risk averse and neutrality fails, then supporting the weaker country can reduce the probability of war rather than make war more likely, even though the weaker side will now make higher demands and reject more proposals in favor of war.