A few minutes past 9 a.m. on Monday morning, United Auto Workers (UAW) president Shawn Fain called Local 1700, roughly sixty-eight hundred of whose members work at Stellantis’s Sterling Heights Assembly Plant (SHAP) in Sterling Heights, Michigan.

“When we looked at the numbers, Stellantis has the least money on the table right now at the Big Three,” he told the leadership of the local, which has for years been a stronghold of militancy and reform efforts within the union. “At 10 a.m., we’re asking you to take your workers out on strike.”

“We were waiting for you to tell us so, ten o’clock it is,” replied the voice on the other end of the line.

“Save the American dream, because a lot of us are having nightmares,” said one Sterling Heights Stellantis worker in a video released by the union later that day. He spoke outside the plant’s gates, having just walked off the job. “No bucks, no trucks,” chanted the workers who produce the company’s best-selling RAM 1500 trucks as they walked the newly formed picket line. It was just after 10 a.m.

In less than an hour, Stellantis had lost its largest and most profitable plant to the UAW’s “stand-up” strike.

This morning, the union struck again. This time, the target was General Motors’s Arlington Assembly Plant in Texas, that company’s largest and most profitable plant. The move came just hours after GM reported third-quarter earnings of $3.5 billion.

“Another record quarter, another record year,” said Fain in a statement announcing today’s expansion of the strike. The union noted that “GM’s offer lags behind Ford, proposing a two-tier wage progression, the weakest 401(k) contribution offer on the table, a deficient COLA [cost-of-living allowance], and other shortcomings.”

Rather than having all 150,000 workers covered by the Big Three (Stellantis, Ford, and General Motors) walk off the job simultaneously when their contracts expired on September 15, the UAW has been calling on specific shops to “stand up and strike,” making for an escalating work stoppage over time. (The concept is an homage to the groundbreaking sit-down strikes that first built the UAW). With today’s escalation, forty-five thousand autoworkers are now on strike across the country, spanning eight assembly plants and thirty-eight parts distribution centers in twenty-two states.

The tactic is a sort of guerrilla warfare, a means of building pressure on the Big Three, who find themselves vulnerable to further escalation, while slowing the depletion of the union’s strike fund in case the work stoppage drags on. I initially had some concerns about the approach, worrying that keeping the majority of autoworkers on the shop floor without a contract could divide the union by isolating strikers (and angering those who wanted to strike but were not called upon to do so) and weakening its economic impact on the companies.

Those downsides still exist — some workers have been on strike for over a month, relying on the union’s $500-a-week strike payments to stay afloat as their counterparts in other plants continue to make regular union wages, a risky dynamic for an organization built on solidarity — but they must be considered alongside the advantages of the strategy: workers who are still on the shop floor have been acting to strengthen the strike, there is plenty of money left in the strike fund, and the cumulative effect has led all three companies to increase their offers to include raises of 23 percent over the life of the four-year contract (a significant improvement over their initial offers, though nowhere near the 40 percent desired by the union).

Additionally, there has been significant, if uneven, movement on a host of other priorities: the reinstatement of cost-of-living allowances (though the formulas advanced thus far by the companies remain insufficient in the union’s eyes), speedy conversion of temporary workers to full-time employment, the elimination of pernicious tiers that were introduced following the Great Recession, the right to strike over plant closures, and, in the case of General Motors, folding current and future electric vehicle (EV) battery plants into the national master agreement (though after the UAW announced that last breakthrough, which represents a major victory, GM refused to confirm it, suggesting bargaining-table wrangling is still ongoing).

For a while, though, even the stand-up strike had settled into a routine. The UAW negotiating committees and the automakers bargained at the tables throughout the week, and on Friday mornings, Fain went live on Facebook to update the membership. During his address, he’d announce which additional locals would be selected to walk off the job in a few hours if the companies failed to make what the bargaining team considered sufficient progress.

Fain’s broadcasts were routinely delayed, with members grousing and joking in the comments about potential reasons for his tardiness. But the cause was employer panic: automakers would ring up union leadership shortly before the Friday morning broadcasts to volunteer new proposals, hoping to spare themselves from being targeted for an escalation that week.

Now, the strike has gotten unpredictable, scuttling company slow-walking of proposals until just before the informal Friday morning deadline. The first case of the shake-up was on the evening of October 11, when Fain called out Ford’s largest shop, the Kentucky Truck Plant in Louisville, after the company brought what he described as “the exact same offer they brought to us two weeks ago.” Within moments, eighty-seven hundred members of Local 862, workers who produce Ford Super Duty pickups, Ford Expeditions, and Lincoln Navigators, were on strike.

As for Monday’s escalation at the Sterling Heights Assembly Plant, Stellantis is not happy. A spokesperson told the Detroit Free Press that the company is “outraged” by the expansion, which took them by surprise; they had offered a new proposal on October 19 and say they were waiting on a counter from the union. But the UAW says Stellantis has the cheapest package of economic proposals — wage progression, temporary worker pay and conversion to full-time work, and COLA — despite boasting the highest revenues and profits of the Big Three, and that its decision to strike the Sterling Heights Assembly Plant was about those proposals taken as a whole.

Now, with five thousand workers at GM’s Arlington plant walking off the job too, that means the most profitable assembly plants at each of the Big Three are on strike. Ford, having lost the Kentucky Truck Plant last week, is expected to report its third-quarter earnings this week as well. JPMorgan estimates that the company’s losses thus far from the strike are around $145 million, with fourth-quarter losses expected to balloon to more than $500 million at each company.

UAW members want contracts, but ones that reflect what they deserve. Absent that, the companies can expect to keep bleeding money. As the union has put it, “record profits, record contracts” (a slogan that even Joe Biden, who walked a picket line with UAW members in September, has repeated). Until workers get such an offer, no one knows when or where they will strike next.