I honestly think the US military would have more problems with having foreign nationals working on a military project than many of the foreign nationals themselves. I think it's difficult to get a security clearance if you're not a citizen, and it may even be hard if you're a dual citizen.
I would think that naturalized US citizens would have the same interest in US national security as native-born Americans. It's a little racist to suggest that they don't, and it would be a little disingenuous for them not to.