Donald Trump has refused to say that he’d back a Nato ally if they were under attack, suggested that South Korea and Japan should not be protected by the US and defended Russia’s annexing of Crimea. Under his presidency would the US still be the world’s policeman? We discuss this along with the prospect of a Hillary Clinton presidency and ask how much her foreign policy will differ from President Obama’s. Monocle’s Steve Bloomfield is joined by Richard Shirreff, Nato’s former Deputy Supreme Allied Commander Europe, Xenia Wickett from Chatham House and one-time Kremlin advisor Alexander Nekrassov.