We build a model of tacit collusion between firms that operate in multiple markets to study the effects of trade costs. A key feature of the model is that cartel discipline is endogenous. Thus, markets that appear segmented are strategically linked via the incentive compatibility constraint....

We augment the canonical neoclassical model of trade to allow for interstate disputes over land, oil, water, or other resources. The costs of such disputes in terms of arming depend on the trade regime in place. Under either autarky or free trade, the larger country (in terms of factor...