DETROIT — Turns out no one keeps a secret as well as General Motors’ leadership.

On Nov. 20, the automaker’s board of directors approved a massive cost-cutting plan that included shuttering two assembly plants in the United States, one in Canada and two U.S. propulsion plants by the end of next year. Combined with white-collar cuts, about 14,000 hourly and salaried jobs are affected.

GM waited until Monday to tell the world its plan, though the news that GM would close its plant in Oshawa, Ontario, leaked out late Sunday.

Some workers expressed anger at learning about the plant closures from news reports or texts, though GM told the Free Press on Wednesday that it gave the UAW a heads up Monday morning before its 10:30 a.m. public announcement.

“How they kept this a secret is shocking to say the least,” said Ivan Drury, senior manager of industry analysis at Edmunds.

Given that the automaker said it will continue to hire people for jobs related to the development of electric vehicle and autonomous vehicle technology even as it cuts other jobs, Drury warned, “There’s definitely more to come, but it depends on where GM places its bets for the future.”

Expect more job cuts and other operational shifts next year, he said. “All those are possible until the full plan is laid out,” said Drury.

Adding to the unknown is GM’s new chief financial officer, Dhivya Suryadevara, who took the role Sept. 1. Analysts said she likely played a big role as an architect to this plan.

A document GM filed Monday with the Securities and Exchange Commission noted that GM will report pretax charges of $3 billion-$3.8 billion related to the plan, mostly in fourth quarter and first quarter earnings. A GM spokesman confirmed the filing was referencing the plan GM announced Monday.

“Board approval is part of a process for certain decision making and once we have board approval we make sure we inform our employees first and other impacted constituents,” said Pat Morrissey, GM spokesman.

Morrissey said GM told employees, local union leadership and plant management in person the details of the plan early Monday, before calling a midmorning news conference.

But one of the plants to be shuttered, GM’s Detroit-Hamtramck plant, was closed Monday for the Thanksgiving break. Some of its 1,500 workers learned their jobs are in jeopardy through media reports later. Many were shocked and angry.

“You tell the world before you tell us,” line worker Dnitra Landon, pulled over in her 2017 Buick Encore before she clocked into the Hamtramck plant Tuesday morning, told the Free Press. “How come we don’t get to know before the world?”

The UAW was equally surprised that GM kept the plan hushed for a full six days, but the UAW has “long been concerned about the strategic investments without flexibility of product drive train in U.S. plants and the continuous movement of product by GM, such as the [Buick] Envision in China and product announcements in Mexico,” UAW spokesman Brian Rothenberg said in an email to the Free Press.

GM will close Detroit-Hamtramck, Lordstown in Ohio and Oshawa in Ontario by the end of 2019. Including 645 jobs at transmission plants in Warren and near Baltimore, more than 6,200 hourly jobs are at stake.

Most UAW workers will have an opportunity to transfer to other factories, including Flint and Arlington, Texas, where in-demand trucks are produced.

The plants being idled make cars that are out of favor with consumers, including the Chevrolet Volt, Cruze (made in Lordstown) and Impala, the Buick LaCrosse and Cadillac XTS.

In addition to the production cuts, GM said it will reduce its North American white-collar workforce by about 8,000. The deadline passed on Nov. 19 for a voluntary buyout for those workers. GM said 2,250 employees have asked to take the offer. That means as many as 5,750 workers could be cut if the company keeps to its announced total. The cuts are expected in mid-January.

Rothenberg said that the UAW discussed the affected plants with GM in the past and drew a clear “line in the sand on U.S. plants.”

“This was long planned through intentional strategic investment decisions and product movement over our objections,” said Rothenberg. “They may have kept the news about it quiet, but this was planned and had to be gradually executed long before sales numbers were known.”

Industry experts said GM’s secrecy about the cost-cutting plan is impressive, but the plan itself should not be surprising.

“One-shift plants are not financially sustainable,” said Kristin Dziczek, vice president of Industry, Labor & Economics at the Center for Automotive Research in Ann Arbor.