Senior diplomats from South Korea, China and Japan met in Seoul on Wednesday to address mutual tensions and pave the way for the first meeting of their foreign ministers for three years
South Korean Deputy Foreign Minister Lee Kyung-Soo told his Chinese and Japanese counterparts, Liu Zhenmin and Shinsuke Sugiyama, that trust "has not taken root" between the three major East Asian economies.
While relations between China and South Korea are probably stronger than they have ever been, both have major problems in their ties with Japan due to similar, yet separate, historical and territorial disputes.
As a result, trilateral cooperation "hasn't stably settled" and can be shaken "easily, at any time," Lee said in a statement released to the media.
The gathering in Seoul was aimed at preparing the first meeting later this month of the three countries' foreign ministers since April 2012.
If that meeting is successful, it could lead to a three-way leadership summit later in the year.
Sugiyama said the three nations are expected to discuss the issue of holding a trilateral summit at their foreign ministers' meeting in Seoul.
"Basically we are anytime ready" for the three-way summit, which has not been held for years, he told reporters.
South Korean President Park Geun-Hye has held two summits with Chinese President Xi Jinping but shunned any formal talks with Japanese Prime Minister Shinzo Abe.
Abe and Xi broke the ice with a frosty handshake on the sidelines of the Asia-Pacific Economic Cooperation forum in November, but relations remain strained.
Japan and China have long been at odds over the sovereignty of uninhabited islands in the East China Sea, which Japan administers and calls the Senkakus, but which China claims as the Diaoyus.
Relations soured in 2012 when the Japanese government angered China by nationalising some of the islands.
Since then, Tokyo and Beijing have routinely butted heads over the issue, with official Chinese ships and aircraft regularly testing Japanese forces.
Seoul-Tokyo ties have always been problematic given the bitter legacy of Japan's 1910-45 rule over the Korean peninsula.
As well as a dispute over some South Korea-controlled islets, Seoul feels Tokyo has yet to fully atone for the excesses of its colonial rule and the forced recruitment of South Korean women to wartime military brothels.