WhatsApp now has more than 2 billion users globally, according to Facebook — and the company says it “will not compromise” on the messaging app’s end-to-end encryption, despite warnings from law enforcement officials.

WhatsApp, which Facebook acquired for $19 billion in 2014, uses strong crypto to keep information sent over the service private, “helping protect you from hackers and criminals,” according to the social-media giant. No one, not even Facebook, can read messages or listen to calls on WhatsApp, it claims.

With 2 billion users, up from 500 million when Facebook bought it, WhatsApp is the company’s second-biggest app after Facebook itself, which had 2.5 billion monthly users as of December 2019.

“Strong encryption is a necessity in modern life. We will not compromise on security because that would make people less safe,” Facebook said in announcing the 2 billion-user milestone.

But Facebook’s plans to more widely use strong encryption across its family of apps has drawn concern from government officials, including U.S. Attorney General William Barr, who fear the messaging tools could be used by criminals and terrorists. “Companies should not deliberately design their systems to preclude any form of access to content even for preventing or investigating the most serious crimes,” Barr, along with top law enforcement officials from the U.K. and Australia, wrote in a letter to Facebook CEO Mark Zuckerberg last fall.

Facebook has stepped up efforts to monetize WhatsApp’s massive user base. Last fall, WhatsApp launched a feature for small businesses to showcase their products. But WhatsApp doesn’t hold a candle to Instagram in terms of earnings power. Facebook has said Instagram has over 1 billion users — and Instagram represented more than a quarter of Facebook’s 2019 revenue, pulling in around $20 billion last year, per a Bloomberg report.

Meanwhile, the encryption features of WhatsApp doesn’t mean it is impervious to security breaches, however. Last month U.N. forensic experts, after reviewing an analysis commissioned by Amazon CEO Jeff Bezos, said the evidence suggested Saudi Crown Prince Mohammed bin Salman was behind a hack of Bezos’ iPhone via WhatsApp “in an effort to influence, if not silence, The Washington Post’s reporting on Saudi Arabia.” Bezos had received a video through WhatsApp from the Saudi leader’s personal mobile phone in 2018, which allowed Bezos’ phone to be tracked, according to the analysis. The Saudi government has denied involvement in the alleged hack.

The exec running WhatsApp is Will Cathcart, who previously was in charge of running the Facebook app. He was named to the post after former WhatsApp head Chris Daniels left the company last year.

Most Americans aren’t aware that Facebook owns WhatsApp. According to a survey last fall by Pew Research Center, only 29% of U.S. adults correctly named Instagram and WhatsApp as owned by Facebook.