National security adviser Robert O’Brien says Beijing has bullied smaller nations by militarising resource-rich waters

The US has condemned Chinese “intimidation” in the South China Sea, alleging it has bullied smaller south-east Asian nations by militarising the resource-rich waters and seeking to control the global trade route.

Speaking at an Asean-US summit in Bangkok, the US national security adviser, Robert O’Brien, said China’s sweeping exclusive claims in the South China Sea – already rejected by the court of arbitration – were illegitimate and a form of realist imperialism.