What gives an F1 team its nationality?

A lot of the F1 world welcomed Haas racing to the track this year, and a lot of hoopla was made about it being an American team. But is it really?
The team is headquartered in Kannapolis but 95% of the engineering, assembly and maintenance work is done by Brits in Banbury in Oxfordshire at the old Marussia facility. As it turns out the only time their F1 cars are in Kannapolis is ahead of the US GP in Austin.
The chassis' comes from Dallara in Italy. The engines come from Ferrari - obviously also in Italy. The drivers are Grosjean (French) and Gutiéerrez (Mexican). The team principal is Guenther Steiner (Italian), the technical directors is Rob Taylor (English) and the chief aerodynamicist is Ben Agathangelou (Greek). Even the chief test driver - Charles Leclerc - is from Monaco.
In fact the only American connection in the team at all is Gene Haas - the owner - and Joe Custer, the COO. Once you get past them, there's nothing American about the team at all.
So is Haas an American F1 team simply because of the nationality of the owner?