Well it isn't if a country agrees to it by definition.

But out of principle, I believe one country shouldn't be operating its immigration facilities on the soil of another nation. Yes, I know the UK does this in France and vice-versa but not as a broadly pursued strategy under the guise of "security" which is what the US has done since 9/11. It's not for passenger convenience. It's an assertion of power and the possibility of refoulement is far greater-- they know that.

That said, I don't want to devolve into a political discussion- my point is that I don't celebrate BRU setting up the facility.