Bro, we were So Viet's allies, and SoViet needed us to restrain you , SoViet could support us billions dollar, so 10 millions for this system was so small.
btw:Russia tech is better than you, if we need some thing important, we will try to buy it, our pilots always can do some Impossible mission like
destroy US's destroyer with Mig 17, shoot dow B-52 with Mig 21, so headless flies(if we don't land based antique radars' guidance`) will not a big problem, bro
Pls don't try to compare your pilots with our , they're diffirent from the other, pls look at US. pilots during VN war and see what happended