Tariff Rate Uncertainty and the Structure of Supply Chains.

We show that reducing the probability of a trade war promotes long-term importer- exporter relationships that ensure provision of high-quality inputs via incentive premia. Empirically, we introduce a method for distinguishing between these long-term relationships|which the literature has termed "Japanese" due to their introduction by Japanese firms|from spot-market relationships in customs data. We show that the use of "Japanese" relationships varies intuitively across trading partners and products and find that the use of such relationships increases after a reduction in the possibility of a trade war. Extending the standard general equilibrium trade model to encompass potential trade wars and relational contracts, we estimate that eliminating "Japanese" procurement reduces welfare about a third as much as moving to autarky. [ABSTRACT FROM AUTHOR]