General Motors said Monday it plans to effectively halt production at a number of plants in the U.S. and Canada next year and cut more than 14,000 jobs in a massive restructuring that will cost up to $3.8 billion.

In response, the United Auto Workers vowed to use "every legal, contractual and collective bargaining avenue" to fight the changes.

U.S. President Donald Trump and Canadian Prime Minister Justin Trudeau also criticized the automaker's decision.

"I am not happy," Trump told reporters on the White House lawn Monday afternoon, speaking of CEO Mary Barra. "You know, the United States saved General Motors. For her to take that company out of Ohio is not good. I think she is going to put something back in soon."

Trudeau took to Twitter earlier in the day to express support for the workers at the Oshawa Car Assembly Plant, in Ontario. "Yesterday, I spoke with @GM's Mary Barra to express my deep disappointment in the closure," he said. She met with National Economic Director Larry Kudlow at the White House hours after making the announcement.

Trudeau

The Detroit automaker said plants in Ohio, Michigan, Maryland, and Ontario will be "unallocated" in 2019 and it will cease operations at two additional plants outside of North America by the end of next year. It will also wind down operations at propulsion plants in White Marsh, Maryland, and Warren, Michigan.

Although the decision effectively shuts down those plants, the company wouldn't say outright that they are closing. Shuttering a plant is a matter of negotiation with the UAW, GM spokeswoman Stephanie Rice said in an email.