Beijing is claiming the authority to decide where Philippine vessels belong, then describing enforcement of that decision as protection.

The Philippines has protested remarks by China's ambassador, its diplomatic representative in Manila, as a thinly veiled threat of force over the South China Sea dispute. The threat gives the territorial argument an immediate recipient: the Philippine crew expected to comply.

Beijing says the disputed islands and reefs fall outside Philippine territory. That assertion supplies the authority Beijing claims for its actions. Accept the premise and a Philippine vessel becomes an intruder before its crew has done anything except arrive.

Beijing describes China's measures as safeguarding sovereignty and maritime rights. Protection, in that account, includes deciding whose presence requires enforcement.

On October 12, this paper described Philippine crews facing encounters that Manila and Beijing explain under different rules. The ambassador's remarks carry that disagreement forward: Manila's objection now concerns a threat as well as a competing claim.

If Beijing enforces that claim through force, a Philippine crew will have to choose between leaving waters its government claims and facing the threatened action.