India now has a bona fide second strike capability, but Pakistan does not. This shifts the balance of power in the region towards a stronger MAD equilibrium between China and India, but it also shifts it decidedly in favor of India in Indo-Pakistani relations.
Back in November, I wrote that without these, they had no second strike capability. Though there were rumors then of this submarine.
When you game this out, it actually stabilizes the situation quite a bit. The previous recipe: poor early warning, short decision times due to proximity, and no second strike capability, launching a nuclear attack could become a dominant strategy as tensions rise. Now, Pakistan does not have a dominant strategy to launch because a second strike would destroy them. Knowing that to be the case, India doesn’t get locked in to their first strike dominant strategy either. So, we don’t have a recipe for an accidental nuclear war anymore.
This doesn’t, however, change the fact that an otherwise non-nuclear conflict could go nuclear under the wrong circumstances. Having said that, this is actually a big improvement in strategic stability for the subcontinent assuming we have a generally non-belligerent India.
Given the United States’ military interests in Afghanistan and its economic ties to India, I think this is preferable to a Pakistani boomer sub.