The US aircraft carrier strike group sailing in the South China Sea is a powerful deterrent to China’s "great wall of sand", according to an expert.

Ports and airfields have been built on reefs in the sea by the rising Asian superpower in defiance of international law.

A Sydney-based expert says the strike group – headed by the aircraft carrier USS Carl Vinson - demonstrates American resolve in standing up to China.

Euan Graham, of the Lowy Institute for International Policy, told Nine.com.au the deployment of US naval forces in the disputed waters was 'business as usual' in one sense.

Fighters on the flight deck of the USS Carl Vinson. (AP).

“But an aircraft carrier makes the point the US is able to match any escalation with China in the area.”

The Carl Vinson carries 72 aircraft - including advanced fighters and surveillance planes - and about 5000 sailors.

The giant vessel - launched in 1980 at a cost of $4.8billion - is escorted by a screen of frigates and missile destroyers.

Dr Graham said the strike group’s deployment shows how seriously the US and its allies take freedom of navigation through the South China Sea.

Admiral Harry Harris, the commander of the US Pacific Fleet, said China was seeking to build a "great wall of sand" to claim the South China Sea.

One of the artificial reefs built by China and fitted with military facilities in the South China Sea. (AP).

US President Donald Trump has nominated Admiral Harris to be the US ambassador to Australia.

While hosting Prime Minister Malcolm Turnbull in Washington on the weekend, Trump said the US “would love to have Australia involved” in naval patrols through the waters.

And next month Britain will send an anti-submarine frigate through the South China Sea to assert freedom of navigation.

The flexing of US military muscle also aims to reassure regional allies who dispute China’s claim of sovereignty there.

The USS Carl Vinson docked off Manila. (AP).

The aircraft carrier’s first leg of its voyage stopped in the Philippines capital Manila.

Chinese authorities have turned away Filipino trawlers from a rich fishing grounds around a disputed shoal.