How long has Trump been in office..? The US can turn away anyone at their discretion, Trump's directive targets certain Nationalities.  His 2nd attempt at blocking these Nationals has been stymied for the time being.  If he gets the wording right, this all changes.  Again, I ask, why take the risk of planning what is likely an end of year school trip when you don't know what the US situation will be? These decisions are prudent and quite frankly, I wouldn't allow my kids to go on a school trip with a US destination right now, even though they are not from the targeted countries. Added benefit is tourist $ will be spent here.