Alarm bells are ringing in some quarters here as China becomes more assertive in waters near the Korean Peninsula. Beijing reportedly wants to include a submerged rock effectively controlled by Korea in regular maritime patrols near the peninsula and deploy its first aircraft carrier there in August. It is also bolstering naval facilities at Dalian port and increasing the number of naval destroyers. The chief of China's State Oceanic Administration was reported as saying in an interview with the official Xinhua news agency on Saturday that Ieo Island is in waters under Chinese control, causing Seoul to call in the Chinese ambassador before deciding whether to lodge an official complaint. The media reports have apparently not been verified. Some pundits say these developments could spell a new maritime threat to Korea. A researcher with a state-run think tank said China's decision to include the submerged rock of Iedo, which lies in the two countries' overlapping economic zones, in maritime patrols "looks 10 to 20 years down the road. If China starts to flex its muscle, a clash with Korea would be inevitable." A government official said while the U.S. is ostensibly shifting its strategic focus on Asia, it is decreasing its military strength in the region, leading to "an inevitable power vacuum" in East Asia and the Pacific, which China may be determined to fill. China has been pursuing a three-stage plan since the 1980s to bolster its naval power. It wants to expand its naval reach to waters near Guam and Indonesia by 2020 and to anywhere in the world by 2050. It is also bolstering a task force fleet to increase its naval mobility. Ieo Island is 149 km off the southern coast of Jeju and is closer to Korea than any other country. Submerged rocks cannot be claimed as any country's territory, but the question is whether the waters are under Korean or Chinese control. Korea is building a maritime research station there. China is also involved in various other territorial disputes, laying claim to the Diaoyu or Senkaku Islands, which are partly controlled by Japan. Lee Dae-woo, a researcher at the Sejong Institute, said, "China is bolstering its naval strength faster than scheduled and is likely to become a major global force around 2020 due to its powerful economic base." These concerns lay behind the decision during the Roh Moo-hyun administration to build a naval base on Jeju Island in order to stem China's increasing naval reach. But now the plan is facing a stumbling block in fierce opposition from leftwing groups.