Facebook said that it would ask its users to tell it which news sources they read and trust to help it decide which ones should be featured more prominently. These responses will help “shift the balance of news you see towards sources that are determined to be trusted by the community,” CEO Mark Zuckerberg explained in a Facebook post.

Meanwhile, Twitter said in a blog post that it would email nearly 678,000 users that may have inadvertently interacted with now-suspended accounts believed to have been linked to a Russian propaganda outfit called the Internet Research Agency (IRA).

The announcements come amid intense scrutiny by U.S. lawmakers over both Facebook and Twitter’s role in letting Russians and others spread misinformation during the 2016 presidential election. The goal, according to U.S. intelligence agencies, was to divide Americans on politically charged issues like race, religion, and gun control.

Zuckerberg announced the Facebook news just days after his company said it would revamp its news feed to show users more family-friendly posts from friends or acquaintances that Facebook believes will spur more user interaction.

“There’s too much sensationalism, misinformation and polarization in the world today,” Zuckerberg said about the polling of users about the sites they have confidence in. “Social media enables people to spread information faster than ever before, and if we don’t specifically tackle these problems, then we end up amplifying them.”

He added: “This update will not change the amount of news you see on Facebook. It will only shift the balance of news you see towards sources that are determined to be trusted by the community.”

It’s unclear how Facebook’s shift will solve the problem of so-called filter bubbles, in which people only see information that aligns with their existing beliefs. Some raised the possibility that crowd sourcing the list of credible news outlets could be manipulated.

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For its part, Twitter minimized the impact of the Russian-linked accounts, saying that they merely represented “two one-hundredths of a percent (0.016%) of the total accounts on Twitter at the time.”

“However, any such activity represents a challenge to democratic societies everywhere, and we’re committed to continuing to work on this important issue,” Twitter said.

Twitter has said that it had discovered 3,814 IRA-connected accounts in total, including 1,062 accounts that it uncovered just recently. It said it had also identified 50,258 bot accounts linked to the Russian government that spread misinformation during the 2016 election, including 13,512 accounts found just recently.