Leaders of some of the world’s most valuable tech companies were apoplectic after President Donald Trump announced on Thursday that the United States would withdraw from the Paris climate accord, a landmark global agreement to reduce greenhouse-gas emissions and prevent the planet from heating to dangerous levels. Tesla C.E.O. Elon Musk, who had threatened to leave the president’s advisory boards if he did not uphold President __Barack Obama's__environmental commitments, promptly resigned. “Am departing presidential councils,” he tweeted Thursday afternoon. “Climate change is real. Leaving Paris is not good for America or the world.” Apple C.E.O. Tim Cook, who had pleaded with Trump earlier in the week, also issued a blistering statement. “I spoke with President Trump on Tuesday and tried to persuade him to keep the U.S. in the agreement. But it wasn’t enough,” he wrote in an e-mail to employees. “Climate change is real, and we all share a responsibility to fight it.”

Although Silicon Valley has feuded with Trump before—particularly over his attempts to ban immigration from Muslim-majority countries and place limits on visa programs—the president’s decision to abandon the historic, 195-nation climate deal seemed to push tech leaders over the edge. Marc Benioff of Salesforce, which was among 25 companies (including Adobe, Intel, Microsoft, Facebook, Apple, and Google) that placed full-page, pro-Paris agreement ads in The Wall Street Journal and The New York Times, wrote that he was “deeply disappointed” and declared that his company would “double our efforts to fight climate change.” Google’s Sundar Pichai, Microsoft’s Brad Smith, and a representative for Uber also said they were “disappointed,” while Twitter C.E.O. Jack Dorsey called the decision “an incredibly shortsighted move backwards by the federal government.” Amazon released a series of tweets asserting the company’s commitment to combatting climate change, and Facebook’s Mark Zuckerberg slammed Trump’s announcement as “bad for the environment, bad for the economy, and it puts our children's future at risk.”

Not every tech company is taking as passionate a stand. IBM, Intel, and Dell all said that their C.E.O.s will remain on the president’s business advisory council, even though they support staying in the Paris agreement. Still, temperatures are running high in Silicon Valley, where the vast majority of executives, entrepreneurs, and venture capitalists already had a fraught relationship with the president. Nor is it clear whether that relationship is salvageable. The Trump administration is currently trying to convene a second major tech summit on June 19 with industry leaders to brainstorm ways to modernize the government’s I.T. infrastructure. But with C.E.O.s like Musk and Disney’s Bob Iger resigning from the president’s advisory councils, pressure will likely be intense on other corporate heavyweights to stop working with the White House in protest.