Whether or not the Saudi government played a role in the 9/11 attacks — and we may never know — for a leading U.S. presidential candidate to claim that they did, not once but twice, had to be seen to be believed. And yet, astonishingly, a little over a year later, it is to the Kingdom of Saudi Arabia that Trump has chosen to make his maiden foreign voyage — rather than to Canada or Mexico, as every president since Ronald Reagan has.