WASHINGTON (WRIC) -- U.S. Sen. Mark Warner (D-Virginia) has sent a letter to the leadership at Valve, the company behind the popular video game distribution software, Steam, after the Anti-Defamation League (ADL) recently published a report alleging the platform is "rife with extremism and antisemitism." The ADL report, released on Thursday, Nov. 14, claimed to have identified millions of unique instances of extremist and hateful content, including anti-semitism, white supremacism and idolization of terrorist groups and mass shooters. The report recommended Valve make significant changes to its moderation policies as a result. In his letter, Warner called for Valve to respond to a series of questions pertaining to claims made in the report. "My concern is elevated by the fact that Steam is the largest single online gaming digital distribution and social networking platform in the world with over 100 million unique user accounts and a userbase similar in scale to that of the ‘traditional’ social media and social network platforms," Warner wrote in his letter. "Steam is financially successful, with a dominant position in its sector, and makes Valve billions of dollars in annual revenue. Until now, Steam has largely not received its due attention as a de facto major social network where its users engage in many of the same activities expected of a social media platform." Warner's letter also notes this is not the first time Steam has been accused of poor moderation policies. Valve received a Senate letter in 2022 that identified similar instances of extremist ideologies on the platform. "We have seen on other social networking platforms that lax enforcement of the letter of user conduct agreements, when coupled with a seeming reluctance by those companies to embrace the spirit (namely providing users with a safe, welcoming place to socialize) of those same agreements, leads to toxic social environments that elevate harassment and abuse," Warner's letter reads. "You should want your users (and prospective users) to not have to wonder if they or their children will be harassed, intimidated, ridiculed or otherwise face abuse." 8News has reached out to the Valve Corporation for comment but has not yet received a response.