Elon Musk warned Twitter employees Thursday to brace for “difficult times ahead” that might end with the collapse of the social media platform if they can’t find new ways of making money.

Workers who survived last week’s mass layoffs are facing harsher work conditions and growing uncertainty about their ability to keep Twitter running safely as it continues to lose high-level leaders responsible for data privacy, cybersecurity and complying with regulations.

That includes Yoel Roth, Twitter’s head of trust and safety — a previously little-known executive who became the public face of Twitter’s content moderation after Musk took over and who had been praised by Musk for defending Twitter’s ongoing efforts to fight harmful misinformation and hate speech. An executive confirmed Roth’s resignation to coworkers on an internal messaging board seen by The Associated Press.

The developments were part of another whirlwind day in Musk’s acquisition of the social media platform. It began with an email to employees from Musk on Wednesday night ordering workers to stop working from home and show up in the office Thursday morning. He called his first “all-hands” meeting Thursday afternoon. Before that, many were relying on the billionaire Tesla CEO’s public tweets for clues about Twitter’s future.

“Sorry that this is my first email to the whole company, but there is no way to sugarcoat the message,” wrote Musk, before he described a dire economic climate for businesses like Twitter that rely almost entirely on advertising to make money.

“Without significant subscription revenue, there is a good chance Twitter will not survive the upcoming economic downturn,” Musk said. “We need roughly half of our revenue to be subscription.”

At the staff meeting, Musk said some “exceptional” employees could seek an exemption from his return-to-office order but that others who didn’t like it could quit, according to an employee at the meeting who spoke on condition of anonymity out of a concern for job security.

The employee also said Musk appeared to downplay employee concerns about how a pared-back Twitter workforce was handling its obligations to maintain privacy and data security standards, saying as CEO of Tesla he knew how that worked.

Musk’s memo and staff meeting echoed a livestreamed conversation trying to assuage major advertisers Wednesday, his most expansive public comments about Twitter’s direction since he closed a $44 billion deal to buy the social media platform late last month and dismissed its top executives. A number of well-known brands have paused advertising on Twitter.

Musk told employees the “priority over the past 10 days” was to develop and launch Twitter’s new subscription service for $7.99 a month that includes a blue check mark next to the name of paid members — the mark was previously only for verified accounts. Musk’s project has had a rocky rollout with an onslaught of newly bought fake accounts this week impersonating high-profile figures such as basketball star LeBron James and the drug company Eli Lilly to post false information or offensive jokes.

In a second email to employees, Musk said the “absolute top priority” over the coming days is to suspend “bots/trolls/spam” exploiting the verified accounts. But Twitter now employs far fewer people to help him do that.

An executive last week said Twitter was cutting roughly 50% of its workforce, which numbered 7,500 earlier this year.

Musk told employees in the email that “remote work is no longer allowed” and the road ahead is “arduous and will require intense work to succeed,” and that they will need to be in the office at least 40 hours per week.

Twitter’s ongoing exodus includes the company’s chief privacy officer, Damien Kieran, and chief information security officer Lea Kissner, who tweeted Thursday that “I’ve made the hard decision to leave Twitter.”

Roth’s resignation is a “huge loss” for Twitter’s reliability and integrity, said his former coworker and friend Emily Horne.

“He’s worked incredibly hard under very challenging circumstances, including being personally targeted by some of the most vicious trolls who were active on the platform,” said Horne, who oversaw global policy communications at Twitter until 2018. “He stayed through all of that because he believed so deeply in the work his team was doing to promote a public conversation and improve the health of that conversation.”

Cybersecurity expert Alex Stamos, a former Facebook security chief, tweeted Thursday that there is a “serious risk of a breach with drastically reduced staff” that could also put Twitter at odds with a 2011 order from the Federal Trade Commission that required it to address serious data security lapses.

“Twitter made huge strides towards a more rational internal security model and backsliding will put them in trouble with the FTC” and other regulators in the U.S. and Europe, Stamos said.

The FTC said in a statement Thursday that it is “tracking recent developments at Twitter with deep concern.”

“No CEO or company is above the law, and companies must follow our consent decrees,” said the agency’s statement. “Our revised consent order gives us new tools to ensure compliance, and we are prepared to use them.”

The FTC would not say whether it was investigating Twitter for potential violations. If it were, it is empowered to demand documents and depose employees.

In an email to employees seen by the AP, Musk said “Twitter will do whatever it takes to adhere to both the letter and spirit of the FTC consent decree.”

“Anything you read to the contrary is absolutely false. The same goes for any other government regulatory matters where Twitter operates,” Musk wrote.

Twitter paid a $150 million penalty in May for violating the 2011 consent order and its updated version established new procedures requiring the company to implement an enhanced privacy protection program as well as beefing up info security.

Those new procedures include an exhaustive list of disclosures Twitter must make to the FTC when introducing new products and services — particularly when they affect personal data collected on users.

Musk is fundamentally overhauling the platform’s offerings and it’s not known if he is telling the FTC about it. Twitter, which gutted its communications department, didn’t respond to a request for comment Thursday.

Musk has a history of tangling with regulators. “I do not respect the SEC,” Musk declared in a 2018 tweet.

The Securities and Exchange Commission recently examined for possible tardiness his disclosures to the agency of his purchases of Twitter stock to amass a major stake. In 2018, Musk and Tesla each agreed to pay $20 million in fines over Musk’s allegedly misleading tweets saying he’d secured the funding to take the electric car maker private for $420 a share. Musk has fought the SEC in court over compliance with the agreement.

The consequences for not meeting FTC’s requirements can be severe — such as when Facebook had to pay $5 billion for privacy violations.

“If Twitter so much as sneezes, it has to do a privacy review beforehand,” tweeted Riana Pfefferkorn, a Stanford University researcher who said she previously provided Twitter outside legal counsel. “There are periodic outside audits, and the FTC can monitor compliance.”

AP reporters Frank Bajak and Marcy Gordon contributed to this report.