By Kalea Hall, David Shepardson

DETROIT (Reuters) -Stellantis NV said on Thursday it was temporarily laying off 900 workers at five U.S. facilities after President Donald Trump’s tariffs were announced, and temporarily pausing production at an assembly plant in Mexico and one in Canada.

The maker of Ram trucks and Jeeps said the U.S. plants affected are powertrain and stamping facilities that provide parts for the two factories in Mexico and Canada that are being idled. Stellantis (NYSE: STLA ) shares were down 7.7% at $10.40  in New York trading at midday on Thursday, in line with a broad decline in U.S. stocks on fears of an all-out trade war.

Stellantis’ Windsor Assembly, where the Chrysler Pacifica and Voyager minivans and Dodge Charger Daytona are made, will be down for two weeks while Toluca Assembly in Mexico, where the Jeep Compass and Jeep Wagoneer S are made, will be down for the month of April, the company said.

About 4,500 workers at Windsor will be impacted by the idling. Workers at Toluca will continue to report to work and get paid but will not make vehicles, according to the company.

Automakers are trying to figure out how to respond to a massive 25% import tax on imported autos that took effect on Thursday. The base U.S. tariff rate for automotive imports is 2.5%. Automakers importing vehicles from Canada or Mexico can deduct the value of U.S. parts from the 25% levy.

In a letter sent to employees on Thursday morning, Antonio Filosa, Stellantis’ chief operating officer for the Americas, said the company is "continuing to assess the medium- and long-term effects of these tariffs on our operations, but also have decided to take some immediate actions, including temporarily pausing production at some of our Canadian and Mexican assembly plants. Those actions will impact some employees at several of our U.S. powertrain and stamping facilities that support those operations."

In February, Stellantis said it was pausing work on its next-generation Jeep Compass compact SUV including the retooling of Brampton Assembly in Canada, which is designated to build the vehicle.

United Auto Workers President Shawn Fain said in a statement on Thursday that “Stellantis continues to play games with workers’ lives. As we’ve shown time and again, they’ve got the money, the capacity, the product, and the workforce to employ thousands more UAW members in Michigan, Indiana, and beyond. These layoffs are a completely unnecessary choice that the company is making.”

Lana Payne, president of Unifor, the Canadian union representing Stellantis workers there, said in a Thursday statement: "Unifor warned that U.S. tariffs would hurt auto workers almost immediately and in this case the layoffs were announced before the auto tariff even came into effect. Trump is about to learn how interconnected the North American production system is the hard way, with auto workers paying the price for that lesson.”

The White House declined immediate comment on the Stellantis temporary job cuts.