> Since WW2 we have had an unprecedented period where major world powers have not gone to war directly and this is a direct result of the American hegemony.

No. It's a result of nuclear deterrance (ie. doctrine of M.A.D.)

> The job of the NSA is to keep the USA in a position of power economically and politically to help stabilize the world.

I think you mean just to keep the US in power. The US destabilizes most countries in which it 'intervenes'. That's the point though, the more countries are broken up, the less likely anyone will challenge the US.