China and the U.S., the world's two largest economies, have been locked in a tit-for-tat tariff fight over the last year, levying duties on each other's imports worth hundreds of billions of dollars in the last few months. Increasingly strong fears of an all-out trade war have inspired exporters to push forward shipment dates — a phenomenon called front-loading. In fact, freight prices for containers going from China to the U.S. have surged more than 100 percent from a year ago as of the beginning of December. Exporters and logistics executives have confirmed the shifting of trade routes as factories rush to fulfill orders before a tariff hike. Some industry experts fearing that a full-blown trade war could hurt shipping volumes – and, in turn, bottom lines for container shipping lines.