Washington (Agencies): Facebook officials on Tuesday said the company is using a range of techniques including artificial intelligence to counter Russian operatives or others who use deceptive tactics and false information to manipulate public opinion.

The officials told reporters in a telephone briefing they expected to find such efforts on the social network ahead of the U.S. mid-term elections in November, but declined to disclose whether they have already uncovered any such operations.

Facebook has faced fierce criticism over how it handles political propaganda and misinformation since the 2016 U.S. election , which U.S. intelligence agencies say was influenced by the Russian government, in part through social media.

The controversy has not abated despite Facebook initiatives including a new tool that shows all political advertising that is running on the network and new fact-checking efforts to inform users about obvious falsehoods.

But the company reiterated on Tuesday that it will not take down postings simply because they are false. Chief Executive Mark Zuckerberg last week drew fire for citing Holocaust denials as an example of false statements that would not be removed if they were sincerely voiced.

Tuesday’s briefing, which included Nathaniel Gleicher, head of cybersecurity policy, and Tessa Lyons, manager of Facebook’s core “news feed,” came just before the publication of an internal staff message from Facebook’s outgoing chief security officer that was sharply critical of many company practices.

The note by Alex Stamos, written in March after he said he was going to leave the company, urged colleagues to heed feedback about “creepy” features, collect less data and “deprioritize short-term growth and revenue” to restore trust. He also urged the company’s leaders to “pick sides when there are clear moral or humanitarian issues.”