Russia.
If true, this is a huge news.
Doubt it is Russia, to be honest. I know Russia is a close ally of India but Russia is the last country looking to get into too much in others affairs, specially considering a lot of their interests like with China as well. If Israel is there, I think the only other world power involved is America; they were in open support of India doing the strikes, America sees India as a potential counter to China, I don't have a single doubt if they are willing to help India and co-operate as they have openly shown to gain leverage and counter Chinese influence.