China's new marine law has a broad arm that could lead to conflict with the US and Japan.
Before entering "Chinese territorial waters," Beijing requires foreign vessels to give notice, supplying maritime authorities with precise information such as the ship's name, call sign, present position, next port of call, and projected arrival time.

It may appear to be a legitimate request, especially if the ship is transporting hazardous items, until you examine what "Chinese territorial seas" entails.
Under its widely disputed and far-reaching nine-dash line, Beijing claims sovereignty over extensive swaths of the South China Sea, as well as disputed islands in the East China Sea.

Will China try to implement the new law in contested seas, for example? If it does, Pacific nations such as Japan and the US are almost certain to refuse. In such a scenario, the question soon becomes, "How will China respond?"
As of September 1, five types of foreign vessels — submersibles, nuclear-powered vessels, ships carrying radioactive materials, ships carrying bulk oil, chemicals, liquefied gas, or other toxic substances, and the ostensibly catch-all "vessels that may endanger China's maritime traffic safety" — will be required by law to provide detailed information to state authorities when entering "Chinese territorial waters."