DETROIT (AP) — President Donald Trump’s trade wars threaten to claim a casualty on the home front: the American auto industry.

If the president goes ahead with 25% taxes on imports from Canada and Mexico on Tuesday, he will disrupt more than $300 billion in annual U.S. automotive trade with its two neighbors, wreck supply chains that have been operating for decades and likely push up the already-forbidding price of new cars.

The tariffs pose an “existential” threat to North American auto production, said David Gantz, a fellow at Rice University’s Baker Institute for Public Policy. They will push up “the cost of everything that’s imported from Mexico or Canada that goes into a car assembled in the U.S.”

Kelley Blue Book says Trump’s tariffs could raise the U.S. price of the average new car — already approaching $49,000 — by $3,000 or more. The price of some full-size pickup trucks could shoot up by $10,000.

The economic pain would intensify if Canada and Mexico counterpunched with tariffs on American exports.

“The economic impact of a sustained 25% tariff on Canada and Mexico would be severe, with full tit-for-tat retaliation likely to push Canada and Mexico into a recession and the U.S. to a point of stagnant growth,” Andrew Foran of TD Economics wrote. Foran estimates that 25% tariffs would push down auto sales by 13.6% a year in Canada and 10.6% in the U.S.

Since 1965 — when the U.S. and Canada eliminated tariffs on each other’s autos and auto parts — North America has turned into an integrated auto manufacturing powerhouse. Mexico was brought into the fold by a 1994 regional trade pact and another one negotiated by Trump himself in 2020.

Much of the production has moved to Mexico. Ford, for example, manufactures the small Bronco Sport SUV and Maverick pickup in Sonora in northwestern Mexico. Stellantis makes the Jeep Compass and Wagoneer S at a plant in Toluca, west of Mexico City, which has been in operation since 1968. General Motors turns out GMC and Chevrolet pickups at a plant in Silao in central Mexico.

Just over half the 8 million cars and light trucks the United States imported last year came from Mexico (No. 1 at almost 3 million) and Canada (No. 4 at 1.1 million). Canada and Mexico are also the top two foreign markets for U.S.-built cars and light trucks, accounting for 53% of America’s auto exports.