Mark Zuckerberg spent last week dragging Apple about how it could run an ecosystem for VR apps, but now it seems he’s chosen a different target: on Monday, he posted a picture of an ad for WhatsApp on Instagram, along with a comment about how the platform is more secure than iMessage. Will Cathcart, head of WhatsApp, also posted a tweet thread going over many of the same talking points.

The ad, which is shown at Pennsylvania Station in New York City, is relatively simple, making fun of the green bubble / blue bubble dichotomy and urging users to use WhatsApp instead so they can use end-to-end encryption to message privately. In his post, however, Zuckerberg is more direct, saying that WhatsApp is “far more private and secure than iMessage, with end-to-end encryption that works across both iPhones and Android, including group chats.” He also points out a few features, like disappearing chats and end-to-end encrypted backups, that WhatsApp has and iMessage doesn’t.

Meta isn’t the only company giving Apple a hard time about iMessage. Google has been pushing Apple to adopt RCS, a successor to SMS, in its Messages app. So far, Apple doesn’t seem to have any plans to do so, with CEO Tim Cook telling users to just buy the people they want to communicate with an iPhone. It’s always possible that its stance could change, though, if WhatsApp becomes a substantial competitor in the US.

The privacy ad campaign is a big push for Meta. Spokesperson Vispi Bhopti told The Verge that it “will appear on broadcast TV, digital video, outdoor, and social across the United States,” and billboards will be popping up in New York, San Francisco, and Los Angeles. Earlier this year, the company made it clear that it wants to grow WhatsApp’s userbase in the US; while it has 2 billion users worldwide (as basically all of our international readers point out in the comments of any article about iMessage’s importance), it’s not the de facto messaging service in America. Meta comparing WhatsApp to something that people are familiar with doesn’t seem like a bad way to go, in theory.

Meta has marketed WhatsApp based on privacy and security before; earlier this year, it posted an ad that compared sending SMS messages to using a mail carrier that opened your letters and packages. The fact that iMessage falls back to SMS and that it can’t be used to securely message people with Android phones is a fair critique of Apple’s privacy-centered advertising around the iPhone. It also doesn’t help matters that you use the same Messages app to send both secure and insecure messages, something that Signal recently said it would stop letting you do because it was confusing.

Zuckerberg’s also correct that iMessage doesn’t have disappearing messages (though iOS 16 introduced the ability to take back messages up to two minutes after you sent them, assuming the person you’re talking to has the most up-to-date software), nor are its backups end-to-end encrypted. As privacy experts have warned, the latter point means that law enforcement agencies could technically get access to your iMessage history if they have a subpoena or warrant, as long as you — or the person you were messaging with — have Messages in iCloud turned on.

Of course, perception is everything in advertising, and Meta has a... let’s say, less than stellar reputation when it comes to privacy. Under Zuckerberg’s post and the Doubt Delivered video, there are several comments asking why anyone would trust WhatsApp: “seems like whatsapp would do exactly that. it’s owned by Facebook lolol,” one user said on the ad about carriers opening your mail. Another user responded to the Penn Station ad by telling Zuckerberg that “I’m happy as long as all of my data is shared with your advertisers 💕”

WhatsApp seems solid for privacy from a technical perspective, but Meta has a massive uphill battle when it comes to PR, especially when it’s going up against the “what happens on your iPhone stays on your iPhone” company. The “sharing data with advertisers” comment shows how people’s perceptions of Meta don’t exactly reflect its business model of keeping your data for itself and selling its ability to target its users with ads.