how far back in history do you read? It was amerika that saved pakistan in 1971 and armed Pakistan to the teeth in 1965 that it became so brazen to attack india and almost won. This is global politcs, there are no real friends and allies and the biggest neighbor India is not China or Russia its the USN parked in the IOR. The USN and USAF could litterally bomb the crap out of India with out consequence. You think thats something the old socialist, Nehru elites in the Rajha Sabha don't think about? You are naive.
USA does tail everything India puts in the water just find yourself a INS Chakra crew. As far as Arihant targeting Pakistan I think thats a logical thing to do since this a test of deterrence not a real one. Arihant was a first a prototype/testing/training vessel smaller than whats really coming in the future and the K-15 is not originally designed for dropping nukes. We know this because the Soviets also had similar missiles designed to target USN battle groups. India does not need a ballistic missile to drop nukes on Pakistan, thats not an opinon, its a fact! India does not need a 700-1000 km missile to drop nukes on China, its not effective and Agnis reach more of China. There for logic dictates the Arihant and K-15 have similar role like the Oscar subs of USSR/Russia. If Arihant and future SSNs can make USN in IOR blink, PLAN and PN won't be a problem. Su-30MKI, Agni 5'/6s, Brahmos, these things are not designed to deter China. Publicly India will claim the China threat, but in reality its the USN whom are strong enough to beat India to a dark age. Imagine if the US has a bad day with Indian diplomats.