The strike by 3,500 Mack Truck workers at plants along the Atlantic coast is part of the largest upsurge in the class struggle in the United States in more than three decades.

When they walked off the job on Saturday, workers at Mack joined more than 46,000 General Motors workers engaged in the first extended nationwide strike at the auto giant in nearly 50 years. The following day, they were joined by 2,000 copper miners in Texas and Arizona. Today, they will be joined by over 30,000 teachers and school support staff in Chicago.

But the United Auto Workers union is working to isolate the strikes at Mack and GM and sabotage them at the earliest opportunity. The UAW kept Mack workers on the job well after the expiration of their contract on October 1, in spite of an overwhelming strike authorization vote by workers.

Even before the Saturday strike deadline at Mack, the UAW was moving to end the walkout at GM on the company’s terms. The UAW-GM tentative agreement announced Wednesday reportedly has only two 3 percent wage increases, which work out to less than the rate of inflation over the life of the contract. It will leave closed all but one of the five plants the company tabbed for closure last December. It will almost certainly include a sharp rise in the use of temps, with a “pathway” for full-time status as a fig-leaf.

By the UAW’s own admission, the issues facing Mack Truck workers are almost identical. Outstanding issues in the negotiations include “wage increases, job security, COLA, wage progression, skilled trades, shift premium, holiday schedules, work schedules, health and safety, seniority, pension, 401(k), health care and prescription drug coverage, overtime, subcontracting and temporary and supplemental workers,” according to a statement by UAW Secretary-Treasurer Ray Curry, who heads the union’s Heavy Trucks Department.

In other words, Mack is demanding wholesale concessions in wages, benefits and working conditions, confident that it will have the assistance of the UAW in enforcing them.

The UAW’s actions at General Motors are a warning to Mack Truck workers. The corrupt union bureaucrats are following the same playbook – after trying to avoid a strike at all costs, they are now seeking to wear down workers on the picket line to pave the way for a concessions deal, subjecting them to starvation rations from the UAW strike fund and enforcing a total information blackout.

In the clearest sign it is preparing a sellout, the UAW is isolating Mack strikers by keeping workers at other companies, and even other subdivisions of Mack’s parent company, Swedish-owned transnational Volvo Trucks, on the job.

Significantly, the UAW has refused to call out the sprawling Volvo Trucks New River Valley facility in Virginia. The factory employs more than 3,000 workers, who operate under a separate contract from Mack Trucks, which does not expire until 2021. The plant produces all of the Volvo-branded heavy trucks sold in North America and is the largest Volvo Truck producer in the world.

The purpose of keeping workers staggered out on separate contracts with different durations and different expiration dates is to prevent a united struggle, weakening the position of workers in each bargaining unit in order to force through concessions.

No less than three wage tiers are stipulated in the Volvo New River Valley contract, with the bottom tier topping out at a paltry $21 per hour, varying slightly depending on the position. This will effectively be consolidated into two tiers by the end of the contract, primarily by eliminating wage increases for second-tier workers after 2018.

As at General Motors, a key goal of Mack Truck management is to maintain labor flexibility. The company has a history of moving facilities up and down the East Coast, resulting in layoffs for some while forcing others to uproot themselves to follow their jobs.

In 2009, the company moved its assembly operations from New River Valley, Virginia, to its current location in Macungie, Pennsylvania. It also consolidated its corporate headquarters with the North American headquarters of Volvo, resulting in the loss of hundreds of jobs.

According to Pennsylvania’s Morning Call, Mack is likely planning to open a new facility in Salem, Virginia, and has been advertising for engineering jobs in the area for months. The UAW has not made an official comment on the plans, even though it may threaten jobs at the Macungie assembly plant.

“We know about it,” one local union official told the news website. “We’re not against it. We understand the company needs to keep making products and keep making money. We just want to have a part in that. But we know about it. We don’t have too many details on it yet.”

This sums up the attitude of the UAW as a whole, which defends the “right” of the company to make a profit, and is concerned only that this is done with the partnership of the UAW.

On the picket line, the UAW is enforcing a gag order on workers. Local 677, which covers the Macungie plant where most of the strikers are located, posted instructions on its website ordering workers, if asked what their demands are, to “state only that the reason we are picketing is to protest the Company’s unfair treatment of its workers – do not say anything else.” Workers are banned from speaking to the press; instead, the local is instructing them to “refer questions from the media to the picket captain.”

Mack Truck workers must move now to break through the UAW-imposed isolation and broaden their struggle. They must form rank-and-file factory committees to take the initiative out of the hands of the union, which is a bought-and-paid-for tool of management at Mack Truck no less than at General Motors.

Such committees will lay the framework for the broadest mobilization of the working class, establishing the unity of Mack Truck workers with GM, Ford and Fiat Chrysler workers, Volvo Truck, Daimler and Freightliner workers, and the entire working class throughout the world.

On Thursday, October 17 at 7:00 p.m. Eastern Time, the WSWS Autoworker Newsletter is hosting an online meeting to provide a strike update and discuss the strategy and perspective needed to secure workers’ interests. We urge all Mack and Volvo Truck workers to attend. To participate, sign up at wsws.org/autocall.