Ours is an impotent state lacking the will to protect its citizens.
This is a low-intensity war waged by elements which are not nation-states and consequently responses must be different. We cannot really rely on regular judicial and international treaties to bring them to justice.
There is no real way to prevent these things from happening. Its far too easy to perpetrate such attacks. But what we can and should do is to raise the stakes. Track each of these dogs down and eliminate them whereever they are. If necessary have them assassinated if we lack the muscle to twist the arms of the nation-states harbouring them.
Its time India left its pseudo-nonviolent passive role and defended its citizens.