MANILA/WASHINGTON - The US expects more encounters at sea with Chinese navy vessels, said the captain of a US coastal combat ship that has patrolled the disputed South China Sea and met a Chinese ship last month.

The countries have agreed codes to help understand each other and talk via radio, said Commander Rich Jarrett, commanding officer of the USS Fort Worth.

The language used is very similar to that used 20 years ago with the Soviet Union, the US' former Cold War foe, he said.

The Fort Worth deployed the codes when it unexpectedly met a Chinese vessel near the disputed Spratly islands during a May patrol of the South China Sea.

It was the first time a US littoral combat ship had operated in waters around the islands, which are claimed by various countries including China, the Philippines, Vietnam and Malaysia.

"There is a language barrier between China and the United States," Commander Jarrett said. "Having a common language... is helpful... it does help avoid any kind of miscalculation."

The US military's publication Stars and Stripes reported the ship was followed closely by a Chinese frigate. The Fort Worth is taking part in a military exercise with the Philippines off the east coast of Palawan this week, near the South China Sea.

China is mounting a serious effort to challenge US military superiority in air and space, forcing the Pentagon to seek new technologies and systems to stay ahead of its rapidly developing rival, Deputy Defence Secretary Robert Work said on Monday.

The Pentagon's chief operating officer told aerospace experts that China was "quickly closing the technological gaps", developing radar-evading aircraft, advanced reconnaissance planes, sophisticated missiles and top-notch electronic warfare equipment.

BLOOMBERG, REUTERS