Subaru suddenly halted production of a massive operation in Japan that sells vehicles to American customers after discovering a potential steering defect.

The Japanese automaker has temporarily stopped production of the Subaru Forester and Subaru Crosstrek, its second- and third-most popular American models, respectively.

If the production shutdown continues, the automaker could eventually face shortages of vehicles at U.S. dealerships.

Production at the company's single plant in Japan shut down a week ago, according to Reuters.

Subaru won't resume production until Monday at the earliest, Subaru spokesman Dominick Infante told USA TODAY in an email.

Start the day smarter:Get USA TODAY's Daily Briefing in your inbox

The issue stems from a power steering defect discovered in Crosstrek and Forester vehicles. The defect may affect about 10,000 vehicles in the U.S., "but that number may be smaller" and the vehicles haven't been sold to customers, Infante said.

"The power steering unit issue was discovered very early, and countermeasures are being put in place," Infante said. "Subaru Corporation can confirm that no vehicles with the affected power steering units will be sold to US customers until the vehicles have been repaired."

The issue has not yet affected Subaru's U.S. plant in Indiana.

It's unclear whether the disruption could affect Subaru's sales. The brand has been red hot in the U.S., recording an 11th straight year of growth in 2018 and 85 straight months of year-over-year sales increases.

And the Crosstrek was a key reason why. Its sales rose 31 percent in 2018 to 144,384 vehicles. Sales of the Forester fell 3.4 percent to 171,613, trailing the brand's top seller, the Outback, by about 7,000 units.

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.