Facebook, Twitter, Google and Microsoft are leading an all-star tech summit that will focus on how social media companies can avoid hackers once again using those platforms as tools to influence national elections.

The gathering was not publicly announced, but a source familiar with the meeting confirmed it was taking place to Fortune.

Facebook has been actively trying to lay new groundwork for election meddling after findings of Russian interference in the 2016 election, announcing new policies and conducting internal investigations into the extent of the interference. Twitter has been under more scrutiny after it reportedly deleted Tweets that could have been useful to investigators.

Buzzfeed cited an internal email from Facebook’s head of cybersecurity policy, Nathaniel Gleicher, outlining three areas of focus for the meeting: What the companies have done to prevent interference; the problems each company faces; and whether the meeting should become a regular occurrence.

The gathering is expected to take place at Twitter’s San Francisco headquarters.

In February, a 37-page indictment issued yesterday by special counsel Robert Mueller said that numerous examples of false or misleading social media activity were engineered by Russia’s Internet Research Agency, as part of a plan to “defraud the United States by impairing, obstructing, and defeating the lawful functions of the government through fraud and deceit” beginning as early as 2014.