Under US law, if you buy a kit from Trumpeter that was manufactured in China, normally the value of the tariff applied to the kit would be assessed according to the tariff applied to China regardless of the country of export.

Exporters are supposed to identify country of manufacture on the customs label (Customs Form 7501) in addition to country of export.

Under US law, it doesn't matter where you bought the kit. It only matters where the kit was made.

Here's one good explanation:

https://aomeara.com/country-of-origin-vs-country-of-export/