. >> reporter: houseli intnce committee democrats have published some 3500 plus ads,ts even and pieces of content thathe russian internet research agency ran on facebook anden instagram betwe 2015 and 2017 in anffor to electis. some oth ent are legitimate events such as rallies and protests that were organized by americans but promoted by the russians. >> this is a popblem with an platform with 2.1 billion people on the system and 6 million advertisers. it's really hard to police and, again, i think that, you know, this just shows you the complexity of what they've created. >> reporter: the ads, which were seen by over 33 million facebook users, target a range of divisive issues ranging from anti-hillary clinton issues to the debate around immigration and anti-gun control ads. these k says they gave ads to congress so they could better understand the extent of russian interference in the last u.s. presidentia election. in the run up to the election facebook was more focused on typical cyber security attacks and they were slow to spot this pe of information interference. facebook saying