A new law would unshackle China’s coastguard, far from its coast

THE ZHAOTOU-CLASS cutter may be a lowly coastguard ship. But it is no pushover. At 12,000 tonnes, it is the world’s largest vessel built for such use. It looms over most American or Japanese destroyers. Its roomy deck accommodates two helicopters, a 76mm gun and a thicket of other weaponry. China has two of them. One is deployed on its east coast. The newest, CCG 3901 (the letters stand for “China Coast Guard”), set sail in 2017 on its maiden patrol of the South China Sea, its designated sphere of operation. Nowhere around China’s shores are waters more contested. The arrival of the behemoth is intended to make a point: China backs its claims in that area with a panoply of steel.

Soon CCG 3901 will have extra ammunition. In November China published a draft law that would empower the coastguard to demolish other countries’ structures built on Chinese-claimed reefs, and to board and expel foreign vessels. In some circumstances it could even fire on hostile ships. The deadline for public comment expired as The Economist went to press.

Over the past decade, the seas around China have been roiled by rival activity and enmity. In the East China Sea, Chinese vessels have been probing waters around the...