Members of the Fancy Bears hacking group, allegedly linked to Russian military intelligence unit GRU, began creating fake Facebook accounts to amplify stolen e-mails in July 2016, according to a new report by The Washington Post. Sources familiar with the company’s investigation into Russian infiltration told The Post that Fancy Bear hackers, also known as ATP28, created two accounts called DCLeaks and Guccifer 2.0 that helped spread the e-mails stolen from the Democratic National Convention.

Facebook is understood to have contacted the FBI at the time of the discovery, but determined that the accounts as financially motivated and not linked to foreign governments. After dismissing claims that the Facebook had been used to influence the election as “crazy,” CEO Mark Zuckerburg was reportedly summoned by President Barrack Obama and asked to take the matter more seriously.

The social media giant has since discovered that Russian-linked accounts had been purchasing ads targeting certain districts and demographics during the election. They were able to remain undetected by using the network’s self-service tool to bypass company employees.

Zuckerburg announced in a statement on Thursday that Facebook is going to review how its tools are used by political campaigns. He said:

“I care deeply about the democratic process and protecting its integrity… I don’t want anyone to use our tools to undermine democracy. The integrity of our elections is fundamental to democracy around the world. That’s why we’ve built teams dedicated to working on election integrity and preventing governments from interfering in the elections of other nations. And as we’ve shared before, our teams have found and shut down thousands of fake accounts that could be attempting to influence elections in many countries, including, recently, in the French elections.

“Now, I wish I could tell you we’re going to be able to stop all interference, but that wouldn’t be realistic. There will always be bad people in the world, and we can’t prevent all governments from all interference. But we can make it harder.”

He also revealed a new plan to ensure that Facebook is a “force for good” in democracy, and can effectively identify and remove problematic content. It includes:

• Actively working with affected governments in ongoing investigations – as well as conducting their own
• Making political advertising more transparent
• Strengthening their ad review process
• Increasing investment in security
• Expanding partnerships with election commissions around the world
• Adapting anti-bullying systems to combat political harassment
• Working specifically with the German government to protect the integrity of their (now-passed) elections

“We are in a new world, he added. “It is a new challenge for internet communities to deal with nation-states attempting to subvert elections. But if that’s what we must do, we are committed to rising to the occasion.”