Why? said the thing about the F-16 already.. They wouldn't sell/share their blueprints and other things, but they would sell the ships. Also, the US and several European countries are currently working together on the making of a brand new aircraft (can't remember the name atm) that is extremely high-tech and expensive.. The US COULD make it by themselves, but they are sharing the knowledge, and in effect the responsibility of manufacturing it, with other countries.