Trump is massaging his xenophobic base in such a way as to keep a campaign promise at the lowest cost to himself. Thus, his exclusion from this ban of nations which have actually sent terrorists to our country (causing more than 3000 deaths since 9/11), because those nations host Trump businesses. Trump is looking forward to 2020. As we see, this giant screw-up is scaring away the best and the brightest, with little positive result since those nations have no history of exporting terrorism to the US.