Leadership in South Korea faced mounting pressure to pick sides in an ongoing controversy over territorial rights to the South China Sea ahead of important summits with regional allies, the Korea Times reported Thursday. Tensions in the South China Sea have reached a boiling point in the region, after a U.S. naval ship sailed through an area that China has claimed as its own territory.

The 750 small islands that are called the Spratly Islands, though small and unpopulated, are valuable as they sit at the cross-section of several major trade routes. The surrounding waters have yet to be explored thoroughly and could contain valuable resources, such as oil and minerals. 

China has made the largest land claim, with Malaysia, the Philippines and other neighboring countries also submitting claims. Despite the matter never having been resolved, China has sparked anger by building artificial islands in order to beef up its sovereignty claim over the territory.

Relations between South Korea and China have grown increasingly amicable through the years, while the U.S. also stands as an important economic and political ally. The United States has refused to recognize Chinese sovereignty in the region, treating the area as international waters and sailing through it, leaving South Korea increasingly caught in the middle.

South Korean President Park Geun-hye is set to meet with Chinese leadership Saturday and the Japanese Prime Minister Abe Shinzo Monday. Japan is a close ally with the U.S. and is expected to push Park to support Washington over Beijing.

Japan was expected to lobby on behalf of U.S. interests in preventing China's land claim, policy experts told the Korea Times. "Prime Minister Abe may bring up the issue during the meeting with Park, because Japan wants to highlight it on behalf of the U.S. government," said Bong Young-shik, a researcher at the Asan Institute for Policy Studies.