Before revision:  We then show that economic benefits from international trade provide incentives to form alliances in ways that restore stability and prevent wars, both by increasing the density of alliances so that countries are less vulnerable and by removing the incentives of countriesto attack their allies. In closing, we examine historical data on interstate wars and trade, noting that a dramatic (more than ten-fold) drop in the rate of interstate wars since 1950 is paralleled by the advent of nuclear weapons and an unprecedented growth in trade over the same period, matched with a similar densification and stabilization of alliances,  consistent with the model  .
After revision:  We then show that economic benefits from international trade provide incentives to form alliances in ways that restore stability and prevent wars, both by increasing the density of alliances so that countries are less vulnerable to attack and also reduces countries' incentives to attack an ally. We present historical data on interstate wars and trade, noting that a dramatic (more than ten-fold) drop in the rate of interstate wars since 1950 is paralleled by the advent of nuclear weapons and an unprecedented growth in trade over the same period, matched with a similar densification and stabilization of alliances, consistent with the model .