Kuala Lumpur, Malaysia — The submerged reef would be easy to miss, under turquoise seas about 80 km (50 miles) off Malaysia's Borneo island state of Sarawak.
But two Chinese naval exercises in less than a year around the James Shoal have shocked Malaysia and led to a significant shift in its approach to China's claims to the disputed South China Sea, senior diplomats told Reuters. The reef lies outside Malaysia's territorial waters but inside its 200 nautical mile exclusive economic zone.
The latest incident in January, in particular, prompted Malaysia to quietly step up cooperation with the Philippines and Vietnam, the two Southeast Asian nations most outspoken over China's moves in the region, in trying to tie Beijing to binding rules of conduct in the South China Sea, the diplomats said.
Beijing's growing naval assertiveness could also push Malaysia closer to theUnited States, its top security ally, thus deepening divisions between Southeast Asia and China over the potentially mineral-rich waters.
Malaysia has traditionally played down security concerns in pursuit of closer economic ties with China, its biggest trade partner.
The James Shoal, which China calls Zengmu Reef, is 1,800 km (1,100 miles) from mainland China. It is closer to Malaysia, Brunei, Singapore, the Philippines,Vietnam and Indonesia - nearly all of Southeast Asia - than it is to China's coast.
Nevertheless, Beijing regards those waters as its southernmost territory, the bottom of a looping so-called nine-dash line on maps that comprise 90 percent of the 3.5 million sq km (1.35 million sq mile) South China Sea.
Pictures from China's state media on Jan. 26 showed hundreds of Chinese sailors standing to attention on a warship's deck, backed by two destroyers and a helicopter that was reported to be at James Shoal.
Malaysia's navy chief denied the Chinese media reports at the time, telling state news agency Bernama the ships were far from Malaysian waters, which are rich in the oil and gas that power the nation's economy. He may have been able to deny the incursion because Malaysian forces did not monitor or sight the Chinese flotilla, security analysts said.