Tech giants like Google and Facebook are facing new government scrutiny, after years of enjoying a hands-off approach from legislators and regulators.

The Silicon Valley pillars are increasingly being hit with criticism about their power, lack of transparency and advertising practices.

European Union regulators have long cracked down on Facebook and Google for antitrust and privacy violations and are now openly calling for higher taxes on digital firms in general. Now that pro-regulations mood seems ready to catch on with the U.S. government, as well.

Here are the five biggest issues causing lawmakers to look at the industry in a new, harsher light.

The Russia investigation

Lawmakers are pushing hard for added regulation and oversight of social media companies afterFacebook revealed that a group with ties to Kremlin allies purchased $100,000 of political advertisements during the 2016 election campaign.

Lawmakers in the House and Senate wrote a letter this week to the Federal Election Commission asking that it establish new guidance for how social media companies can mitigate foreign election interference on their platforms.

On Thursday, Facebook said it would take steps to be more transparent with its ads and turned over to federal investigators 3,000 ads purchased by a Russian actor. But Facebook’s self-regulation, seen as an attempt at avoiding government-imposed rules, hasn’t satisfied legislators.

After Facebook CEO Mark Zuckerberg announced the new steps toward ad transparency, aletter surfaced from Sens. Mark Warner (D-Va.) and Amy Klobuchar (D-Minn.) soliciting support for a forthcoming bill that would require digital platforms with over 1 million users to disclose all “electioneering communications” by anyone who spends more than $10,000 on political advertisements.

A spokesperson for Warner said that, while Facebook’s announcement is a step in the right direction, it doesn’t go far enough for the senator.

Warner’s spokesperson noted that while ads were likely a component of potential election interference, experts suggest that fake accounts and pages on Twitter and Facebook seeking to influence voters are a bigger problem.

A new antitrust movement

A growing number of scholars are arguing that the concentration of power in Silicon Valley over private data, public discourse and economic sectors is a threat to the country.

The movement is spearheaded by Barry Lynn, who believes the solution to the concentration of corporate power is to overhaul the legal standard for antitrust enforcement.

Lynn’s argument was thrust into the spotlight over the summer, when he and his team were pushed out of the New America think tank. New America president Anne-Marie Slaughter clashed with Lynn over his criticism of Google, one of the think tank’s biggest donors, The New York Times reported.

Both Google and Slaughter have denied the internet search giant played any role in Lynn’s ouster.

Lynn and his team have since gone independent, launching a stand-alone group called the Open Markets Institute. Their mission is to convince policymakers to target dominant corporations to loosen their hold on the country’s political and economic systems.

Silicon Valley is at the top of their list, and their ideas are making a splash in Washington. Democrats have included a new antitrust agenda as part of their messaging platform.

The idea of cracking down on Silicon Valley companies is also gaining traction with some conservatives, who normally oppose additional government involvement in the economy.

“Our ability to communicate freely with one another in this country, which is the primary basis for being able to protect our democracy, is now threatened in very real ways,” Lynn told The Hill.

Culture wars

When Google fired engineer James Damore last month for writing a divisive internal memo on the company’s diversity initiatives, Republicans of all stripes blasted the internet search giant for what they saw as suppression of a conservative voice in a company known for its close ties to Democrats.

The backlash was similar to what Facebook experienced last year after Gizmodo reported that the company had omitted conservative news stories from its “Trending News” feature.

Zuckerberg later met with prominent conservatives in an attempt to quell that uproar. But there’s still unease in right-wing circles about the power wielded by the tech industry, which tends to be more liberal than other big businesses.

That distrust is evident in the increasing number of prominent conservatives who have advocated a tougher regulatory approach to Facebook and Google. A variety of voices on the right, from Weekly Standard editor Bill Kristol to Fox News host Tucker Carlson and Breitbart News chief Stephen Bannon, have called for tech giants to either be subjected to tougher antitrust enforcement or regulated like public utilities.

Sex trafficking

Perhaps the most imminent headache for the tech behemoths is an anti-sex trafficking bill that has garnered bipartisan support in the Senate.

The Stop Enabling Sex Traffickers Act (SESTA) would cut into the sweeping legal protections that internet publishers enjoy when it comes to content posted by third-party users. The bill would remove that protection for sites that knowingly enable sex trafficking.

The bill, spearheaded by Sen. Rob Portman (R-Ohio), is the product of a nearly two-year Senate panel investigation into sex trafficking ads on the site Backpage.com. The Permanent Subcommittee on Investigations concluded in January that the classifieds site “knowingly facilitated” sex trafficking.

Much of Silicon Valley is opposed to the bill, concerned that it could pose a threat to free speech by opening up legitimate internet platforms to greater liability. But Abigail Slater, general counsel for the Internet Association, which represents Facebook and Google, told the Senate Commerce Committee last week that the industry is open to finding a compromise.

“SESTA is a well-intentioned response to a terrible situation,” Slater said.  “We are concerned that SESTA opens up liability for frivolous lawsuits that do little for victims of sex trafficking.”

Advertising algorithms

Internet companies are also taking heat over the possibility that their ad platforms can be used to discriminate.

Facebook first took criticism in October, when ProPublica revealed that companies purchasing housing ads on Facebook could use the website’s tools to exclude black, Hispanic and Asian-American individuals – a potential violation of housing discrimination laws. Lawmakers, including some members of the Congressional Black Caucus, condemned the ads and called for changes.

Facebook’s ad targeting policies came under fire again this month, when ProPublica found that Facebook allowed advertisers to target advertisements to individuals who had put racist and bigoted terms, like “how to burn Jews,” in their education or work fields.

A follow-up BuzzFeed report found that typing “Why do Jews ruin everything” will lead Google’s ad tool to suggest that an ad buyer also target advertisements to individuals searching for similarly anti-Semitic terms like “the evil jew” and “jewish control of banks.”

Both companies have removed the features and pledged to do better. But to many, the damage has already been done, adding another controversy to the firestorm surrounding the tech giants.