China hawks have the upper hand in the political battle over electric vehicles. They should be wary of overplaying it.

The rules for getting a tax credit on EV purchases in the U.S. changed recently. One difference will help stimulate sales: The credit, worth up to $7,500, is now available at the point of sale rather than at the end of the tax year, meaning it can be used as part of a down payment. Other changes will have the opposite effect. Among new sourcing requirements designed to foster a North American supply chain, battery components manufactured in China, the world’s largest supplier, now make models ineligible.