Facebook is spending so much money hiring moderators to review political ads that it will cancel out the revenue those ads generate in this year’s election cycle, says CEO Mark Zuckerberg.

“We’re essentially going to be losing money on running political ads,” because the company is hiring “thousands” in advance of the 2018 elections, Zuckerberg said in an interview today. “That cost is going to be greater than the money that we make.”

The effort is part of Facebook’s reaction to the 2016 U.S. presidential election, when Russian-sponsored actors attempted to intervene by posting ads — as well as using fake users, accounts and groups.

In the long run, Zuckerberg says, the company will rely on computers and artificial intelligence to intercept objectionable content. But that will take five to 10 years, he said. So for now Facebook needs the help of humans, and that will cost “billions.”

Zuckerberg made those comments during a wide-ranging interview he conducted at Off the Record, an annual gathering of journalists and media executives hosted by The Information, Quartz and BuzzFeed in Menlo Park.

He said the company was reasonably confident it would be able to thwart the efforts of “state actors and fake news trolls” to interfere in the upcoming U.S. elections — in part because it has had success fending off interventions in recent French and German elections, as well as last year’s special Senate election in Alabama.

But he also assumes that Facebook will see more attacks than it did two years ago. “I know that people are going to try to abuse the systems, especially after feeling like they were able to get a [return on investment] doing that in 2016.”