The recent aggressive Chinese behaviour in the South China Sea is worrying many countries: from Vietnam and the Philippines to Japan and the United States.

Some years back, China used to call the South China Sea a sea of peace, friendship, tranquillity and cooperation. However, in recent months, it has undertaken unilateral actions asserting its claims in the South China Sea.

As a rising great power, China and its leaders strongly believe that they should have a sphere of influence in Asia.

The questions are: why is China taking a more assertive stance over territorial claims in the South China Sea that have, in most cases, existed for decades? Why is China using its military muscle in such a provocative way? Is it China’s ambition to push the US navy out of the western Pacific where it has been dominant since World War II?

Some American diplomats think that China’s assertive behaviour will eventually push its neighbours closer to the US but other observers are less sanguine given China’s pivotal role as a trading partner for ASEAN. Either way, the US urgently needs to re-arm it’s toolkit to meet the challenges from China.