The union representing workers at General Motors Co.'s U.S. facilities will stand in the way of the company’s decision to stop production at some plants in any way it can, according to a Nov. 26 statement from the union.

GM announced Nov. 26 that it would be cutting 10,000 jobs and targeting five factories for closure in 2019. Four of the factories would be at facilities in the U.S. where workers are represented by the United Automobile Workers union.

“The...