The United Auto Workers union has once again escalated its strikes against big Detroit automakers, this time adding a factory that makes Ram pickup trucks for Stellantis.

The union says that 6,800 members walked out Monday morning at the Sterling Heights, Michigan, Assembly Plant, a huge profit center for the company.

The newest strike action comes just three days after union President Shawn Fain reported progress in talks with General Motors and Stellantis but said the companies will have to make better offers. No progress was reported with Ford, last week said it had the best offer of the three.

The union went on strike Sept. 15 at one assembly plant from each company. About 40,000 workers are now on strike against all three automakers.