This is not a genuine security issue; it's an economic war by the US on companies with which it can't compete because it's services is so woeful. Rather than up their game, they again unlevel the playing field. Chapter 11, fifth freedoms and now this. Trump is as bent as a three dollar note and he has cowed to the US3 without upsetting Boeing. Otherwise, why would all US operators flying from those nations on the list be exempt from the rule?