The full effect of President Trump's 'America First' doctrine is not yet known, but for economist Jeffrey Sachs, the US dollar is likely to suffer. At a recent conference hosted by Columbia University, Mr Sachs argued that Trump's tariffs and his broader affinity for upending trade agreements and multilateral treaties would diminish the US's role on the world stage. Eventually, he said, we'll see an alternative payments system in which the dollar, euro and China's renminbi share the global reserve currency spotlight.