Oil tanker Alnic MC was detected by the Singapore maritime authorities before its collision with American destroyer USS John S. McCain in Singapore waters on Monday (Aug 21) morning.

The Maritime and Port Authority of Singapore (MPA) said in response to queries from The Straits Times on Wednesday (Aug 23) that its Vessel Traffic Information System (VTIS) had detected only the presence of Alnic MC.

The monitoring system detects and tracks vessels via radar or the Automatic Identification System (AIS) signals, and enables an alert to be sent to vessels in the event of an impending collision and to get them to change course.

Military experts say it is not uncommon for naval vessels to switch off their AIS systems for security purposes. Dr Sam Bateman, a former commodore of the Royal Australian Navy and adviser to the Maritime Security Programme at the S. Rajaratnam School of International Studies, said: “Warships often don’t have their AIS switched on because of security… That is a real problem.”