New York CNN Business  — 

For years, Twitter (TWTR) and Facebook (FB) have enjoyed a healthy rivalry: They’ve competed for acquisitions, talent and advertising dollars, and sometimes gone so far as to copy each others’ features in the never-ending pursuit to grow their audiences.

But the clash between the two tech companies appeared to take on new life this week after Twitter’s decision to place fact-check labels on some of President Donald Trump’s tweets sparked a series of threats, including an imminent executive order regulating social media companies.

The CEOs of the two companies traded criticisms in public. Former employees posted their own jabs on social media. And some legislators were quick to highlight the differences between the approach Twitter and Facebook took, potentially only adding to the tensions.

“We have a different policy than, I think, Twitter on this,” Facebook cofounder and CEO Mark Zuckerberg told Fox News in a clip posted online on Wednesday. “I just believe strongly that Facebook shouldn’t be the arbiter of truth of everything that people say online.”

Hours later, Twitter CEO Jack Dorsey appeared to push back at the assertion, saying that labeling the tweets with fact checks does not make the social media company an “arbiter of truth.”

“Our intention is to connect the dots of conflicting statements and show the information in dispute so people can judge for themselves. More transparency from us is critical so folks can clearly see the why behind our actions,” Dorsey tweeted Wednesday night.

Others were even more direct. In a series of tweets on Wednesday, former Twitter executive Jason Goldman called Zuckerberg’s statement to Fox News a “bad quote” and added: “Going on Fox to hit Twitter in defense of Trump is really a move. Good look for everyone involved.”

The public clashes between the two companies further cast aside the unified front the tech industry previously tried to present in how it handles misinformation. The Trump tweets in question falsely claimed that the governor of California was sending out mail-in ballots to “anyone living in the state, no matter who they are or how they got there.” Twitter labeled them with a message urging users to “Get the facts about mail-in ballots.” Twitter’s message directly linked to a curated fact-checking page populated with journalists and news article summaries debunking the claim.

Facebook chose to do nothing, even though identical posts appeared on the platform. The company has previously said that politicians are exempt from its third-party fact-checking program.

The combative rhetoric also hints at how high the stakes are for each business as Trump escalates his threats.

The draft executive order being prepared by the Trump administration seeks to curtail the power of large social media platforms including Twitter and Facebook by attempting to reinterpret a critical 1996 law that shields websites and tech companies from lawsuits.

In earlier tweets after Twitter added the fact-check label, Trump threatened to “regulate” or even “close” down social media platforms.

White House press secretary Kayleigh McEnany did draw some distinction between Facebook and Twitter in an appearance on Fox News on Thursday. “There are two models here,” she said. “You have Facebook and you have Twitter and you have Mark Zuckerberg who says it’s not my job to be the arbiter of truth.”

This week isn’t the first time Zuckerberg and Dorsey have been at odds about how to handle political speech on their respective platforms. Dorsey announced last October that Twitter would stop running political ads. His announcement came after Zuckerberg publicly defended Facebook not only allowing political ads, but allowing politicians to lie in those ads.

In his tweets Wednesday, Dorsey said he takes ultimate responsibility for decisions made by Twitter and asked people to “leave our employees out of this.” (Earlier Wednesday, Trump’s two elder sons and White House counselor Kellyanne Conway pointed to tweets made by Twitter employee Yoel Roth in 2016 and 2017 as evidence of Twitter’s alleged bias against the president.)

“There is someone ultimately accountable for our actions as a company, and that’s me,” Dorsey said.

On that point, at least, Dorsey and Zuckerberg seem to be in agreement. “I started Facebook,” Zuckerberg told the Senate in 2018, “I run it and I’m responsible for what happens here.”

Betsy Klein and Seth Fiegerman contributed to this report.