In these threads different Quora users hypothetically analyzing the chances and probabilities of nuclear encounter between India and Pak
For decades India has been working on what is called thecapability – the ability to respond to a nuclear attack. The reason India has been working so hard on navy these days is partly to have a credible second strike.
Given the extent of India’s geography and extent of Pakistan’s capabilities only a fraction of Indian territory would be damaged by the first strike. Pakistan doesn’t have aircraft carriers or nuclear submarines to launch a strong attack on India and has to purely rely on long range missiles, which are fairly inaccurate. Unless Delhi is destroyed, India’s response would have a very swift response. If Delhi is destroyed with no warning, Army has to work on new protocol on the go for taking control.
India’s response would be expectedly brutal. Almost all of Pakistan is easily accessible to Indian bombers [most of population live within 100 miles of Indian border]. This makes things asymmetric. India’s biggest population centers are away from the border in contrast.
India also has a variety of submarine launched missiles like K4 that would start firing from near Karachi.
If Pakistan is proven to be the striker, neither US nor China would come to its help and Indian Navy’s nuclear carriers would have field day launching bombers from the Pakistan’s south while the Air Force would come from the north backing the army’s move from east.
Besides second strike, India is also working to avoid this in the first place: