I am referencing to the start of ww2 in SEA.A bit confused to what you are saying here, but navies are allowed to transit through any open waterway as long as they do not take military action.
All colonial fleets(Netherlands, Royal navy, Australia and the US Asiatic squadron: ABDA) had the same full rights right before the start of the hostilities, but Japan wasn't especially concerned with them. With the start of the hostilities, all these forces(hastily reinforced by two British capital ships) failed to have any impact, and were destroyed in series of naval clashes.
This has ended any allied surface naval activity within region untill well into 1944.
My message is, China isn't anywhere up to such a "cleaning out" operation, right now.
This is what chinese naval buildup can change. Or may not.