As special counsel Robert Mueller issues the first indictments in his investigation into Russian meddling in the 2016 US election, executives of three technology titans will face questioning by Congress this week about Russian use of their platforms.

Representatives from Facebook, Twitter, and Google are set to testify before a Senate judiciary subcommittee on Tuesday, then the Senate and House intelligence committees on Wednesday. The hearings begin just a day after Mueller charged former Trump campaign chair Paul Manafort with 12 counts of money laundering, tax fraud, and foreign-lobbying violations, and former Trump foreign policy adviser George Papadopoulos admitted to lying to the FBI about meetings with Russians connected to the Kremlin. The charges have renewed public interest in an investigation that Republicans in Congress last week said they were close to concluding.

Now, Congress will turn its spotlight on some of the world’s most powerful companies to learn more about how Russians used their technology to influence American voters and what the companies are doing to stop it. The hearings may devolve into partisan squabbling, with Democrats seeking to amplify Russia’s impact on Trump’s election and Republicans downplaying Russia’s influence online. On the off chance that our elected representatives actually want to learn something, we offer this list of questions worth asking:

Are ads really the biggest problem? What about the ways propaganda can spread through ordinary posts?

Facebook’s announcement in September that a Russian propaganda group known as the Internet Research Agency had purchased $100,000 worth of election-related ads sparked additional revelations about how that same group had placed ads on other platforms designed to influence US voters. Since then, Twitter has disclosed that it discovered 200 accounts connected to the group, while Google discovered $4,700 worth of ads linked to Internet Research Agency on its platform.

But it's now becoming clear those ads are only a small part of a much larger problem. Facebook on Tuesday will tell Congress that as many as 126 million people may have been exposed to 80,000 posts from Internet Research Agency over a two-year period, compared with 11.4 million who saw its 3,000 ads, according to the company's testimony, which was acquired by WIRED. A source familiar with Twitter's testimony says the company plans to tell Congress it found 36,746 accounts that "generate automated, election-related content and had at least one characteristic we used to associate them with a Russian account." In other words, they're Russian bots. Between September 1 and November 15, 2016, those accounts generated 1.4 million "automated, election-related Tweets," and an eye-popping 288 million impressions. Twitter also says it's now identified 2,752 accounts linked to IRA, all of which have been suspended. And, in a blog post published before the hearing, Google executives said the company found 18 YouTube accounts connected to IRA that uploaded 1,108 ​videos, "representing ​43 ​hours ​of ​content ​and ​totaling ​309,000 views" in the US between June 2015 and November 2016.

So far, Congress has primarily focused on ways to crack down on digital election ads. But organic posts are far more vulnerable to infiltration.

When did these companies begin actively looking for clues related to Russia?

Cybersecurity researchers at Crowdstrike linked Russia to the hack of the Democratic National Committee as early as June 2016. According to Facebook's testimony, in the summer of 2016, it noticed a cluster of accounts related to a Russian military intelligence group called APT28. Those accounts began creating fake personas with the explicit purpose of disseminating stolen information from a website called DC Leaks. It suspended those accounts and reported several "threats from actors with ties to Russia" to law enforcement before election day.