gCaptain has provided a video screen grab showing AIS (Automatic Identification System) tracks in the Singapore Strait including that of the oil tanker Alnic MC for the time of Monday’s collision with the U.S. guided-missile destroyer USS John S. McCain which apparently occurs about 50 seconds in, you may want to go to full screen.
Note there was no AIS track for the McCain, just as there was no AIS track for USS Fitzgerald at the time of her collision two months earlier.
I appreciate the need for security, but perhaps in highly congested areas in peacetime, it would be advisable to turn on AIS.
Chuck Hill's CG Blog 
An explanation of why it is difficult for merchant ships to “see” warships. https://www.nytimes.com/2017/08/25/world/asia/navy-collision-uss-mccain-oil-tanker.html?hp&action=click&pgtype=Homepage&clickSource=story-heading&module=second-column-region®ion=top-news&WT.nav=top-news
In peacetime, if a warship is operating in an area that is so busy it that it requires a traffic separation scheme, then it seems they should operate their AIS and check in with vessel control systems.
This from the German Navy blog “Marine Forum” suggest the Navy may now have moved to use AIS in congested waters.
“01 September, BLACK SEA, US Navy destroyer „Porter“ has left the Black Sea after 2 weeks of visits to and exercises with allied/friendly navies and „naval presence operations“
(of note: passing the Turkish Straits with its AIS switched on; new safety regulation when sailing narrow waters?) “
The Navy has now directed their ships to operate AIS when in heavily trafficked areas–common sense prevails.