Donald Trump’s special envoy yesterday publicly slapped down Nato’s chief over the idea that Ukraine could be admitted to the alliance. Richard Grenell told secretary-general Mark Rutte he would ‘run into a big buzz saw in America’ if, as Mr Rutte suggested, he tried to make it happen. The spat broke out during an annual Ukraine breakfast on the sidelines of the World Economic Forum in Davos. The event laid bare divisions between those in Mr Trump’s new administration who are pushing for early peace talks with Russia to end the war and others including European ministers who say Vladimir...