US and Japan add pressure on Beijing over the South China Sea and the Senkaku Islands.

US and Japan have joined a battle of diplomatic notes over the South China Sea dispute, adding to pressure on Beijing over its expansive claims in the strategically vital waterway.

In a note verbale – a type of diplomatic communication – sent on Tuesday, Japan’s permanent mission to the United Nations said China’s “drawing of territorial sea baselines … on relevant islands and reefs in the South China Sea” failed to satisfy conditions set out in the UN Convention on the Law of the Sea.

It also accused China of restricting freedom of navigation and overflight in the South China Sea.

Beijing’s claims to most of the waterway were rejected in 2016 by a tribunal in The Hague that ruled several of the land features were “low-tide elevations” without territorial waters.