The Tejas also uses an Israeli Radar. Using an American engine isn't the worst, the Indian Kaveri jet engine doesn't seem to be going anywhere. Jet engines are probably the most difficult engineering feet to master. People say it's more difficult than sending a man to the moon. Only a few countries can produce modern jet engines, USA, Russia, France, UK, and recently China and out of these, only 3 can produce high thrust engines, USA, Russia and China. It took China 30 years to master modern jet engines. They had to rely on Russian engines for their first modern fighter jet J-10, and were even using Russian engines on the early J-20s.