Tariffs have been applied over the years to protect homegrown industries and target competitors who are seen as using unfair trade practices. They impose costs on both importers and exporters and had been in decline until the recent U.S.-China trade war.

The U.S. transport system is badly in need of infrastructure investment, and the country could suffer competitively if the status quo persists.

The Muslim separatist group, based in the Xinjiang province in northwest China, presents a heightening security challenge for Beijing.