US President Donald Trump's deputy National Security Adviser, KT McFarland, has been asked to step down after just three months. <br/><br/>According to media reports, Ms McFarland has been offered the role of ambassador to Singapore instead. It comes days after Mr. Trump removed his senior strategist Steve Bannon from the National Security Council. <br/><br/>Mr Bannon's appointment in January had raised fears that the circle of top advisers was being politicised.<br/>