NATO vs Russia :
In the 80s, the US war machines were the most breath taking. And Russia [then called USSR] far lagged behind.
40 years later. Now it's Russia that's coming up with newer and newer machines with their unique Wow factor. And it's the USA that's lagging behind.
BusinessInsider Article in comment.
"An S-400 can spot even stealth aircraft such as the F-35 and, using a relatively cheap missile, down a jet that costs many hundred times its own value."
Explains why USA is so much opposed to India and Turkey getting the system.