Around 90% of foreigner contractors that come to the USA to set up a factory or do maintenance on a factory are here under weird visa arrangements that the ICE would be able to poke holes in regardless. The right visa doesn’t exist, or impossible to obtain, so he Germans/swiss/japanese/koreans/taiwanese/and Chinese come here on visa waiver or simple B1 visas, or even tourist visas, to get the job the they need done out the way quickly (usually a few days or a week of work). The American visa system for short term work is simply messed up, and it’s much easier to get a visa to do the same thing in China than in the USA (surprise, guess where people decided to set up their factories?). America was really just wink/nudge before (we want you to setup a factory here! But no, we can’t really make the visa situation work out…you know what to do…), but now ICE needs to make their quotas and this is just an easy target for them.

The USA is just a bad place for foreign companies to setup factories: you need an army of immigration lawyers to do it, and be willing spending a lot of time waiting to get the “proper visas” for key personnel. South Korea’s interest in getting those engineers back isn’t just purely empathy based, there are probably only a handful of engineers in Korea that can do what they do (good luck getting that factory going before your term is out, Mr. Trump).

> good luck getting that factory going before your term is out, Mr. Trump

That may well have been the goal in the first place.