'We have learnt a lot since 2016,' says social media giant's founder, likening the task to 'arms race' against Russia, Iran and China

Trump administration said to warn an unnamed entity is behind social media posts falsely claiming US heading to lockdown

Russia has a history of accusing its neighbor of fascism and state-sponsored anti-Semitism

Website of company that boasted it would 'change reality' for clients was registered by Grey Content, an ad firm that creates public service TV spots for Israeli ministries