China patrol ship
AP
It seems that China, or at least part of it, has thrown down the gauntlet in the South China Sea with the announcement that police in the southern island province of Hainan will board and search ships which enter what China considers its territory in the disputed waters.
Before discussing the implications of the "revised regulations," it's helpful to know why China thinks it can commandeer the territory in the first place.  In October James R. Holmes of NamViet News cited the book "How Communists Negotiate" to note that going into negotiations "Chinese communists try to rig the game in their favor"  by trying to force the opposite side to agree to Beijing's bargaining positions as a condition for convening talks.
Currently China's position is that they claim everything within the "nine-dashed line" – which takes in about 90 percent of the South China Sea – and its law enforcement will act to defend it.
In August the Ministry of Foreign Affairs of China stated: "China has indisputable sovereignty over the South China Sea islands and adjacent waters. This is supported by clear historical facts."