I very much doubt there was a collision - if so where is the sub they hit???
I think the collision story is Russian government disinformation in an attempt to save red faces.
The main reason they are not asking for help is national security but I'm sure that national pride is another factor.
I wonder if they are up to something with that sub - apparently half the men on board are officers....surely that is not routine?
Whatever the reasons if they let the crew die when they could so easily ask for assistance it will be an absolute disgrace.