By Kim Young-jin

Concerns are rising over China’s increasing assertiveness in surrounding waters, with analysts saying it could prove a stumbling block in bilateral relations.

Beijing is currently embroiled in diplomatic disputes with Japan, the Philippines and others over sovereignty claims, raising the specter of heightened tension over Ieodo, a submerged reef southwest of Jeju Island.

Analysts have long been wary over how the world’s second-largest economy will behave as its global influence increases, including in the East and South China Seas. They say such concerns prompted Washington’s recent “pivot” toward Asia in its defense policy.

“Its strategy is to build hegemony in East Asia,” Bahng Tae-seop, an analyst with the Samsung Economic Research Institute, said. “In order to do so it needs sea-lane security. They need to protect against greater U.S. engagement and also secure natural resources in the future.”

The strategy has increased concern that a full-blown dispute could erupt over Ieodo, which sits 4.6 meters below sea level. In 2003, Seoul built an ocean research station there, but Beijing continues to lay claim to it.

The issue drew headlines last month following reports that Liu Xigui, the chief of China's State Oceanic Administration, claimed that Ieodo is in waters under Chinese control and is part of areas patrolled by Chinese vessels and aircraft. Beijing took the stance that the sides should demarcate the area's exclusive economic zones through talks.

Seoul expressed confidence that Ieodo would be declared its own given that it is closer to the peninsula than any other country. Worries linger, however.

“We have to be concerned about Ieodo. We should also be concerned about it as a key ally to the United States, which has a role in the region,” the analyst said.

Beijing clashes often with Tokyo over gas fields and a set of disputed islands in the East Sea known as Senkaku in Japan and Diaoyu in China. Tension came to a head in 2010 when authorities in Japan arrested a Chinese trawler captain for colliding with coastguard ships in the area.

Manila and Beijing, meanwhile, are in a showdown over the Scarborough Shoal, some 230 kilometers from the Philippines' main island of Luzon. Both sides have sent ships to the area to assert their sovereignty.

Beijing is reportedly considering military action to back its sovereignty.

Vietnam, as well is protesting a Chinese fishing ban in parts of the South China Sea, that Hanoi considers its own. The sides have also wrangled over an uninhabited shoal.

Analysts note that the territorial disputes have coincided with a reported naval build up on the part of Beijing, raising concerns such action could spark an arms race in the region.