India can not rely on the USA (or the UN for that matter) to protect them. The UN and USA can't even stop Putin from invading The Ukraine. Therefore I don't believe that the USA or UN will be effective in protecting India from Pakistan.
India needs to have a fleet of their own to preserve and secure their borders. With Pakistan and Bangladesh getting subs from China and it is no secret that Pakistan wants to purchase nuclear ballistic missiles from them as well. As much as nobody wants an arms race in the region it is in India's best interests to be able to deter any aggression from Pakistan.
The latest submarine accident proves that India should build its own fleet. The latest accident killed 2 sailors due to toxic smoke aboard they're submarine. In last August 18 Indian sailors were killed in an explosion and fire which sank its submarine. Most of India's submarines are Russian built and antiquated. If India has the resources to do so they should build their own fleet of submarines which would be modern and less prone to malfunction.
While outsourcing can be a great way for your business to save cash, there are some jobs that simply can't be outsourced. Jobs that deal with sensitive information, or that deal with high-profile clients, are best deal with traditional employees rather than outsourced workers. Whether or not you should outsource workers is a matter of common sense.
No, this latest submarine accident does not prove that India should build its own fleet, because occasionally accidents happen. Government will likely take over and do an even worse job. If a company is known to have accidents, no one will want to work for them. The free market can resolve this one way or the other.
This recent incident proves that India should just forget about building a fleet of any kind. I do not think that India should think about building a fleet of any kind. I do not think it is important for their country to do so. I think it is better if they establish allies.