Submarines
I understand the point made by Lonewolf about the US not wanting the positions known of any of its tactical nuclear submarines but there are many types of submarines and I am surprised that considering all the assets deployed there has been no mention of any other types.
For example, Malaysia itself has 2 French built submarines, the Australians have 6 Collins Class subs based in Western Australia, Japan has 16 and heaven knows how many the Chinese have.
As people experienced in SAR have pointed out, it is extremely difficult to spot semi submerged debris even in calmish conditions so surely a submarine at a shallow depth should be able to scan the surface of the sea above it using radar/sonar. There has to be an explanation as to why they are not being used. Taking the 6 Australian ones as an example, it does not seem to make sense that the positions of all have to remain secret as presumably some have to come back to base for resupply and then they would be visible by satellite.
Surely there must be submarines there - anyone have an educated answer/guess ?