Anyhow, using as the definition that's done so moving onto business entities.

When you are crossing a border then all sorts of legal issues can arise and as these are specific to the two countries you are doing business across there is no correct answer here. For example in the EU this may be covered by existing EU agreements and by something entirely different in US-CAN borders.

But as always, follow the money. If it crosses borders that makes the cut as a foreign country (with a possible fine exception like the EU.)

For this, you need a lawyer to navigate all this. It's specific to the countries in question.