I am reading reports that the IRIS Dena was unarmed at the time of its sinking. It was returning home after a joint exercise with the Indian Navy. Moreover, the US had been invited to participate in the exercise and had withdrawn at the last minute, so they would have been aware that participating ships would not be armed. If true, does this constitute yet another war crime, especially as the submarine failed to surface and render assistance to survivors, even though there was no threat to it?