In an interview with Fox News last week, President Trump revealed his inner thoughts about electric cars—not that many had any doubts.

"All-electric is not going to work," he said, referring to General Motors' stated goal to transition to "a world with zero crashes, zero emissions, and zero congestion." The company announced last year that it will launch 20 new hybrid, plug-in, and electric cars by 2023 to meet more stringent emissions standards in China, Europe, California, and elsewhere.

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Referring to GM CEO Mary Barra's announcement of the plan, Trump said, "“They’ve changed the whole model of General Motors. They’ve gone to all-electric. All-electric is not going to work ... It’s wonderful to have it as a percentage of your cars, but going into this model that she’s doing I think is a mistake.”

DON'T MISS: Trump vows retaliation against GM for layoffs

GM announced last month that it would shut down five assembly plants, including the Detroit Hamtramck factory that builds the Chevy Volt and the Lordstown, Ohio, factory that builds the compact Chevrolet Cruze that underpins the Volt. At the same time, the company plans to lay off 15,000 workers. Those workers, in Michigan and Ohio were some of the supporters that handed Trump the election in 2016.

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When GM made the announcement in the end of November, Trump vowed retaliation against the company, and he reiterated that stance last week. “I don’t like what she did," Trump told Fox News, referring to Barra. "It was nasty. To tell me a couple of weeks before Christmas that she’s going to close in Ohio and Michigan, not acceptable to me. General Motors is not going to be treated well.”

As GM as looked to ramp up production in China to meet the country's demand for electric cars, Trump has imposed new tariffs on Chinese-made products to make them harder to import. That has thrown a monkey wrench into GM's plans (and those of other automakers) to sell some of those cars in the U.S.