No he can't lol
A Merchant ship has an IMO number and appears in AIS. The destination,cargo etc etc is all logged in massive databases for legal purposes alongside safety and traffic management.
All traffic destined to China will be stopped or sunk.(we have the submarine fleet big enough to shutdown all shipping lanes) All ships outside shipping lanes (tracked by BOA ISR assets like Tritons) will be hunted down and interdicted.
The Navy gets sound profiles,hullform images via SAR and even ELINT data from the radar and radios. This information is disseminated to Submarines,airplanes etc etc.
WE CHANGE FLAG U NO FIND HAHA
China flags a sizable fleet of vessels as Chinese or from HK. These vessels are on lists with tonnage,draft,freeboard (this information is tracked by the canals and ports authorities too,along side Governments.
Vessels not flagged by China STILL HAVE TO FILL OUT VOYAGE PLANS we created a global system to track ships because of terrorism and the BIG DATA BIG TECH revolution.
nonces the whole lot lol