By Alex Heath

Two of Facebook’s most important executives, Chief Product Officer Chris Cox and VP of WhatsApp Chris Daniels, announced Thursday that they were suddenly stepping down from their roles.

The loss of the two leaders, who together have more than 21 years of combined work experience at Facebook, comes after CEO Mark Zuckerberg recently unveiled a strategy to unify the company’s disparate messaging apps and shift from public posts towards private, encrypted messaging strategy.

Chris Daniels, who led WhatsApp for less than a year, specifically left over disagreements with Zuckerberg’s plan to unify the messaging infrastructure across Facebook’s suite of apps, a WhatsApp employee told Cheddar.

“Chris Daniels was a great leader for us, and because of that, clashed with Mark,” said the employee, who requested anonymity to discuss internal matters. “I buy that they both (Daniels and Cox) were able to choose to leave, but this is Mark's company through and through.”

Both Cox and Daniels were recently promoted into new roles, making their departures all the more surprising. For years, Cox was in charge of Facebook’s main app and revenue-driver, the News Feed, before being promoted last year to lead product development for all of Facebook’s apps, including Messenger, WhatsApp, and Instagram.

Before being promoted to VP of WhatsApp around the same time as Cox, Daniels previously led the social network’s initiative, which helps bring internet access to technologically-emerging countries Facebook has yet to saturate.

Given his experience working in emerging markets like India, where WhatsApp is heavily used already, Daniels was an obvious choice to lead the app, current and former employees told Cheddar at the time of his promotion.

But he and Zuckerberg clashed on a number of topics, most notably the CEO’s recent push to unify apps so that users can talk to each other across services. WhatsApp uses end-to-end encryption by default, making the messages sent by its roughly 1.5 billion users untraceable, while Facebook’s other apps currently don’t.

Facebook declined to comment for this story. BuzzFeed News reported on Thursday that Cox left Facebook over “a disagreement over the company’s product direction.”

Daniels was moved to WhatsApp last year to fill a leadership vacuum left by the two app’s co-founders, Jan Koum and Brian Acton, who sold the app to Facebook for $19 billion and both departed last year over disagreements on how to monetize the service. Investors see WhatsApp as a key driver for Facebook’s future revenue growth. The social network is working on a cryptocurrency to facilitate payments between its users.

Zuckerberg praised Daniels on Thursday as being “one of the clearest and most principled business thinkers I’ve met” in a blog post announcing the two departures. He noted that Cox’s role as chief product officer will not be replaced, and that another longtime executive named Will Cathcart will now lead WhatsApp.

“In his career here, Will has helped lead our teams focused on security and integrity, and he believes deeply in providing end-to-end encryption to everyone in the world across our services,” said Zuckerberg.