In an interview with Washington Post reporters Wednesday, Instagram head Adam Mosseri said he still believes building an app for kids is “the right thing to do.”

Mosseri unexpectedly joined a public discussion The Post was hosting on Twitter about the findings from the Facebook Papers, a trove of internal documents released by a whistleblower. The documents, first obtained by the Wall Street Journal, have shown employee concerns that Facebook, which owns Instagram, valued growth over safety and how weaker moderation in some countries outside the United States leaves the platform vulnerable to abuse by criminal and authoritarian regimes.

Mosseri discussed the social media platforms’ ranking of user engagement, and he addressed the controversial Instagram Kids service, which the company paused development of last month.

Instagram had been repeatedly asked to abandon the nascent project over concerns about privacy, screen time and the mental health of young people. Calls to shut it down escalated after a Journal report showed the company knew Instagram could negatively affect teenage girls.

But on Wednesday, Mosseri said kids are often online anyway, and building a service just for them would give parents more control over how their children use the app.

“I get it’s an easy dunk, to dunk on the idea,” he said. “But I think if you get into the details of this and you look at the actual practical realities, it’s, I think, a much more responsible path than where we are today.”

Instagram has rules against users under the age of 13 and removes them if it finds they’ve made accounts, he said, but age verification is imperfect.

Facebook has already started using artificial intelligence to figure out how old its users are, according to a July blog post from its vice president of youth products, Pavni Diwanji. That information is applied to their accounts on other Facebook products, including Instagram.

The company knows how old people say they are when they put in a birth date to start an account. However, Mosseri said, kids are pretending to be older to sign up for accounts, with and without parental consent. Given how much else the social media company infers about people to better target ads — like interests and political leanings — being able to deduce a real age is plausible. The company’s system looks for cues like people wishing friends a “happy 12th birthday” to flag them as under 13.

But on Wednesday, Mosseri suggested individual apps shouldn’t be the ones to take on age verification. It would be much more efficient to solve the problem at the phone level, he said. Companies like Apple and Google could build in age verification, and any developer could use that to tailor its apps.

“We need to get better at age verification, I think that should happen at the operating system level not the app level,” he said.

Facebook executives have made few public comments since the Facebook Papers became public, though spokespeople have defended the company.

On an earnings call Monday, CEO Mark Zuckerberg called the reporting by a consortium of newspapers “a coordinated effort to selectively use leaked documents to paint a false picture of our company.”