Actually, you said RIL, I did not.
Pipavav was acquired by Reliance Defence and Engineering, RDE. It's under ADAG. It was purchased by Reliance Infrastructure, which is also under ADAG.
http://economictimes.indiatimes.com...ence-and-engineering/articleshow/51243955.cms
Then there's Reliance Defence and Aerospace, RDA.
https://in.rbth.com/economics/defen...space-to-make-200-helicopters-in-india_393195
The Russian government has selected Reliance Defence and Aerospace (RDA), a company owned by Indian billionaire industrialist
Anil Ambani, for a joint venture to manufacture almost 200 Kamov 226T helicopters in India.
All of ADAG's subsidiaries have the name Reliance in them. Like Reliance Power, Reliance Comm, Reliance Capital etc.
So RIL is under Mukesh and has nothing to do with defence. All the defence related stuff is under ADAG. Hence the confusion.