In Malaysia, territorial waters is 12Nm (22.2km) from the Coast. That said, any nation be it the US, or China can technically sail through these territorial waters that is not prejudicial to the 'peace, good order or security of the coastal State' per UNCLOS.

if you tick the following items it will be innocent passage:

(a) any threat or use of force against the sovereignty, territorial integrity or political independence of the coastal State, or in any other manner in violation of the principles of international law embodied in the Charter of the United Nations;

(b) any exercise or practice with weapons of any kind;

(c) any act aimed at collecting information to the prejudice of the defence or security of the coastal State;

(d) any act of propaganda aimed at affecting the defence or security of the coastal State;

(e) the launching, landing or taking on board of any aircraft;

(f) the launching, landing or taking on board of any military device;

(g) the loading or unloading of any commodity, currency or person contrary to the customs, fiscal, immigration or sanitary laws and regulations of the coastal State;

(h) any act of wilful and serious pollution contrary to this Convention;

(I) any fishing activities;

(j) the carrying out of research or survey activities;

(k) any act aimed at interfering with any systems of communication or any other facilities or installations of the coastal State;

(l) any other activity not having a direct bearing on passage.

someone suggested going to war. Attacking a vessel conducting an innocent passage is prima facie against International Law. The West might even sanction you for doing it as a matter of fact...