My FRiend, you are behind the times. Most countries now feel they have right do that, including the USA. It all started with traveling for the purpose of engaging in illegal sex acts, such as with underage partners, but like so many laws, once the precedence is set, more and more actions are criminalized.
There are a lot of Africans/Muslims in all the Scandinavian countries. Malmo, Sweden, will be the first European city to be more than 50% Muslim, - it's just about there now.
That still doesn’t make it truly legal. A nation’s reach ends at it’s border. . .