A flurry of summit meets are taking place in Seoul, starting with a meeting between President Park Geun-hye and Chinese Premier Li Keqiang on Sunday. This was followed by a trilateral summit – the first in more than three years — of Park, Li and Japanese Prime Minister Shinzo Abe on Sunday and the first ever summit between Park and Abe will take place on Monday.

Issues concerning the Korean Peninsula and Northeast Asia were discussed during the Park-Li summit on Saturday, with Park emphasizing the need for North Korean denuclearization and asking China to play a role in bringing about a change in North Korea’s attitude. It is not known if the two leaders discussed the issue of South China Sea, where a U.S. destroyer recently sailed within 12 nautical miles of some of the artificial islands built by China.

A significant outcome of the summit is the statement that the two countries’ ties are growing not only in the economic sphere, but also in the political and security fields. The two leaders are reported to have agreed to strengthen and expand the current strategic partnership. Park and Li also agreed to work toward ratifying the Korea-China free trade agreement, which has yet to be ratified by the National Assembly here, by the end of the year.

Korea and China share a number of common interests, outside the realm of economics. Politically, both countries have been pushing Japan to resolve the issue of Japanese military sex slaves during World War II.

Security wise, China has been playing a significant role in the effort to denuclearize North Korea. A member of the six party talks aimed at North Korean denuclearization, China enjoys a unique position vis-a-vis North Korea as its traditional ally and largest sponsor.

In a sign of broadening cooperation, Korea and China on Saturday signed an agreement that allows sharing of data on atmospheric conditions. With quick availability of such data, Korea will be better able to study and formulate policies for yellow dust and particulate matter that originate from China.

The summit meeting, originally scheduled to last an hour, stretched out to nearly two hours, indicating the scope and depth of the talks Park and Li held. It also indicates cozy relationship between the two countries. As Park pointed out, she has met with Chinese President Xi Jinping, Premier Li Keqiang and Zhang Dejiang, chairman of the Standing Committee of the National People’s Congress this year. Indeed relations with China seems to be on a high note.

But even as Korea-China relations warm, Korea should be mindful of its long-time ally, the U.S. Park treads a fine line as she seeks to expand ties with China at a time when China and the U.S. are at odds on a number of issues.