I want to know the answer to the following question:
What can see stealth aircraft even with RCS?
All the background I'm provided with is that "The newest SAM's have a claimed ability to be able to detect and engage stealth targets, with the most notable being the S-400, which is claimed to be able to detect a target with a 0.05 meter squared RCS from 90 km away.". Is that enough to answer the question?
Answer: no