There is absolutely no way that this or the previous collision was because the warships were unaware of the proximity of other vessels.    What's pretty obvious is that the merchant vessels were being used for a type of drill (shadowing, close pass) and that something went wrong.

They need to re-think the use of civilian vessels for exercises.    It's one thing to put the navy ship and personnel at risk (that's part of the job) but nobody on any civilian fleet signs up for that.