Ram’s parent company is taking steps to build its bestselling truck in Mexico, a move that threatens to inflame the automaker’s frayed relationship with its workers’ union.

Chrysler parent Stellantis is expanding its factory complex in northern Mexico to build Ram 1500 pickup trucks, the Wall Street Journal reported on Tuesday. Stellantis has been building additional factory space next to its existing plant in Saltillo,

Stellantis has been building additional factory space next to its existing plant in Saltillo, Mexico, the report said, citing people familiar with the matter.