President Trump:
Why not include all the years that these European countries have defaulted or paid a small percent to NATO membership that the US had to cover in Military expenses. Why not put a price tag on the Liberation of their country from the Nazis for all the years that they have been Sovereign due to US Intervention by accumulating their GDP, which would have been zero, had the US not liberated them. Give them a balance sheet, and consider that as the already paid purchase price.