Facebook CEO Mark Zuckerberg said in a press briefing on Tuesday that “there’s a lot we don’t know yet” about the motives behind the activity and he did not say whether the groups had spread fake news or propaganda. He would only say that the people behind the accounts were intentionally “misleading people about who they were and what they were doing.”

“Authenticity matters,” Zuckerberg said.

Facebook said that that the Iranian entities targeted Facebook users in Middle East, Latin America, the United Kingdom, and the United States, but it did not cite specific examples of what the organizations had attempted to do.

The company said in a corporate blog post that one unnamed group linked to Iran shared unspecified “content” about “Middle East politics in Arabic and Farsi.” The same organization also shared “content about politics in the UK and US in English,” but Facebook didn’t elaborate further.

Facebook said that it had briefed the U.S. and U.K. governments as well as the U.S. Treasury and State Departments because of ongoing U.S. sanctions against Iran.

Regarding the Russian entities, Facebook said the pages, groups, and accounts it kicked off its service were linked to “sources the U.S. government has previously identified as Russian military services,” but were not connected to Iran. The company said that these “bad actors” focused on politics in Syria and Ukraine and were “spreading pro-Russian and pro-Assad content.”

Zuckerberg said that the company understands that “2018 is a very important election year” and reiterated some of the steps the company is taking to prevent bad actors from sowing discord on its service, like using machine learning technology to filter misleading content.

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“So this is really serious,” he said. This is a top priority for the company.”

In early July, Facebook said it removed 17 Facebook profiles, 8 Facebook pages, and 7 Instagram accounts that were engaging in “inauthentic behavior” leading up to the middterm elections. U.S. Senator Mark Warner said at the time that the “disclosure is further evidence that the Kremlin continues to exploit platforms like Facebook to sow division and spread disinformation, and I am glad that Facebook is taking some steps to pinpoint and address this activity.”

The company is attempting to clean its image and improve the overall security of its service after facing intense criticism for failing to prevent the spread of misinformation in prelude to the 2016 U.S. Presidential election.