BEIJING: A US Navy destroyer docked in Shanghai on Monday in a sign that contacts between the US and Chinese militaries are continuing despite tensions over the South China Sea.

The visit by the USS Stethem follows Chinese protests over the sailing last month of the guided missile destroyer USS Lassen within 12 nautical miles (22 kilometres) of disputed Subi Reef.

The reef has been transformed by Beijing into an island over the objections of other claimants. The US maintains that such man-made islands do not qualify for territorial waters.

The Stethem's commanding officer, Cmdr. Harry Marsh, told reporters that US freedom of navigation operations were routine and shouldn't complicate relationships with the armed forces of other countries.

"Sometimes countries might have some disagreements, yet our navies are able to operate safely at sea," Marsh said.

The visit by the Arleigh-Burke class destroyer to China's financial centre followed a stop in the northern port of Qingdao. The two countries are also planning a combined search and rescue exercise at sea.