By Vanessa Yurkevich and Chris Isidore, CNN

(CNN) — The United Auto Workers union took its most serious shot yet at General Motors in its five-week old strike as 5,000 members walked off the job at a plant in Texas. Arlington Assembly builds GM’s very profitable full-size SUVs, the Chevrolet Tahoe and Suburban, GMC Yukon and Cadillac Escalade.

The targeted strike at GM’s largest plant comes just hours after the company reported third quarter earnings, which grew last quarter despite the strike.

“Another record quarter, another record year. As we’ve said for months: record profits equal record contracts. It’s time GM workers, and the whole working class, get their fair share,” said UAW President Shawn Fain.

General Motors said it achieved those earnings despite losing $200 million during the first two weeks of the strike, and then an average of $200 million a week in costs during the first three weeks of this month. With Arlington going on strike, those weekly losses are likely to jump more than 50%.

GM said there was no reason for an expansion of the strike, that the union and company were making progress at the bargaining table.

“We are disappointed by the escalation of this unnecessary and irresponsible strike,” said the company’s statement. “It is harming our team members who are sacrificing their livelihoods and having negative ripple effects on our dealers, suppliers, and the communities that rely on us. Last week, we provided a comprehensive offer to the UAW that increased the already substantial and historic offers.”

GM says it has offered the UAW a record contract with the pay scale increasing 23% over the life of the contract that runs through 2028, along with cost-of-living adjustments to protect workers from rising prices and larger contributions to their retirement accounts.

“It is time for us to finish this process, get our team members back to work and get on with the business of making GM the company that will win and provide great jobs in the US for our people for decades to come,” said the company.

But Fain had told members last week that despite record offers from GM, as well as Ford and Stellantis, there was more that that the companies could afford to give members. He said the union needed more from the companies in order to make up for past concessions the union granted in contracts in 2007 and 2009, when they were all losing billions, and GM and Stellantis predecessor Chrysler were heading towards bankruptcy and federal bailout.

While the expansion of the strike was without notice, it’s not a complete surprise. The UAW had already taken out the most profitable plants at Ford and Stellantis.

Earlier this month Fain told members that the union was ready to expand the strike to the Arlington plant, and it put those plans on hold when the company gave into a key union demand regarding the work to be done at EV battery plants hat have recently opened or are under construction.

That agreement kept the workers at Arlington on the job for another 18 days until Tuesday. But the union said Tuesday that GM is now lagging behind offers on the table from Ford, and that it needs to expand the strike in order to increase pressure on the company.

“GM’s latest offer fails to reward UAW members for the profits they’ve generated,” said the union’s statement. “It is clear that GM can afford a record contract and do more to repair the harm done by years of falling real wages and declining standards across the Big Three.”

The UAW started the strike September 15 by striking one assembly plant at each company. But the union left open the option of expanding the strike, one plant at a time, as way to increase pressure on the companies. Tuesday’s announcement marks the fifth time the union has increased the scope of the strike.

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