Isn't there some tension there?
Yes. The US has announced that it plans to continue to patrol areas of the South China Sea, a section of the Pacific Ocean near Singapore and Taiwan, over which China has staked a territorial claim. The announcement follows a US mission last week in which the destroyer USS Lassen sailed within 12 nautical miles of Subi Reef, a natural feature landscaped and built on by China. The US does not recognise territorial claims over Subi and other "artificial islands" in the area. The sea has become a flashpoint in generally deteriorating US-China relations.
How did this all come about?
The South China Sea has been a disputed territory for centuries, but competition has got more intense in recent decades. Two island chains in the sea, the Paracels and the Spratlys (Subi is part of the latter) are claimed in whole or part by a range of regional powers including China, Vietnam and Taiwan. Chinese authorities drew a "nine-dash line" in 1947 which stakes claim to a huge range of territory including both island chains, and since then there have been numerous clashes. But since 2014, when China stepped up military exercises and moved to install an airstrip and harbour capable of supporting military craft in the Spratlys, this has escalated. China has moved an oil rig into disputed territory near the Paracel islands, triggering huge protests in Vietnam.
Prospect outlined the escalation in its "Big ideas of 2015" feature last year.
Why is the territory disputed?
China has said that the island chains are "China's historical territory since ancient times.” Many would debate that, but in any case the United Nations Convention on the Law of the Sea (UNCLOS), which China has ratified, generally rejects "historically based" claims. The claim rests on the idea that the informally-defined and fluid Chinese empire once included the island ranges. More recently, the area has grown in importance not just for historic reasons but for the soaring value of its fishing grounds and for the growing evidence of oil reserves under its sea bed. Other claimants' bids vary, but Taiwan, for example, has recently been more conciliatory in tone, launching a "South China Sea Peace Initiative" this year. Some critics have accused the US in focusing too much on China's claims and not on those of its neighbours.
Why does the US care?
The US's official position in this latest scrap is that it is defending the principle of free movement in international waters, which is important for trade. It insists that it is not in this instance wading into the row over regional claims to land per se, but rather demonstrating that building artificial islands doesn't give a country rights over nearby seas. More broadly, the US, in co-ordination with Japan, wants to supply military hardware to regional allies including the Philippines.
