General Motors warned on Friday that expansive U.S. tariffs on imported vehicles being considered by the Trump administration could lead to “a smaller GM” and risks isolating U.S. businesses from the global market.

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.)