From global manufacturers such as Harley-Davidson Inc to small tech startups, companies are scrambling to rework supply chains built for an era of stable, open trade policy that is now under threat.

There’s something irresistible about a clash of titans. The fate of the world hung in the balance during the Cold War standoff between the U.S. and the U.S.S.R. Coke vs. Pepsi once mattered mightily. Ali-Foreman defined a pugilistic era. And then there’s the celebrity spat pitting Taylor Swift against Kanye West. (Look what he made her do.)

At least three U.S. coal shipments on their way to China may end up casualties of the escalating trade dispute after Beijing said it would impose steep tariffs that may kick in before the ships reach their destinations.

Few people consider used plastic to be a valuable global commodity. Yet China has imported 106 million tons of old bags, bottles, wrappers and containers worth $57.6bn since 1992, the first year it disclosed data. So when the country announced last year that it finally had enough of everybody else's junk, governments the world over knew they had a problem. They just didn’t know exactly how large it was.

Mark Gath’s farmhouse in Luverne, Minnesota, sits 30 miles down country roads from Sioux Falls, South Dakota. From that base in the heartland, Gath, a sturdy man in boots and a blue shirt, farms more than 10,000 acres of corn and soybeans with the help of his wife, Leah, and sons Dalton and Stetson. Though his farm is larger than average, he feels squeezed by low commodity prices and the rising costs of seeds, pesticides and equipment. “Everyone is scared out here,” he says.

World Cup barbecues may be under threat as beers, fizzy drinks and meat producers warn of potential shortages caused by a lack of CO2.