Facebook can't afford to repeat the mistakes of 2016.<br /><br />During the 2016 US presidential election, the social network was wildly abused by Russian propagandists. <br /><br />Two years later, America is gearing up for its contentious midterm elections, and Facebook is eager to show progress in its fight against election-meddling.<br /><br />On Wednesday, the Silicon Valley firm invited journalists into its Menlo Park, California headquarters, to tour the "war room". <br />
