International Politics and Import Diversification
研究了1962-2000年间美国与别国政治关系恶化如何影响进口，发现总体影响小，但石油进口会显著远离政治对手，因为石油贸易涉及易被没收的垂直外国直接投资。
This paper examines how international politics affects trade in the absence of empires or wars. We first show that deterioration of relations between the United States and another country, measured by divergence in their United Nations General Assembly voting patterns, reduced U.S. imports from that country during 1962–2000. Though statistically significant, the magnitude of the effect of political distance on trade is small. Indeed, we show that except for petroleum and some chemical products, U.S. imports are not affected by international politics. American firms, however, diversify their oil imports significantly away from political opponents of the United States. Oil trade is often associated with backward vertical foreign direct investment that is subject to the expropriation risk. In contrast to the usual claim that oil is a strategic commodity, we provide suggestive evidence that trade in products when rents are appropriable is more likely to be affected by international politics.