Chinese President Xi Jinping and his South Korean counterpart Park Geun-hye have expressed concern over Japan's recent reinterpretation of an article in the country's constitution that renounces war.
As the Chinese leader is on the last leg of a two-day visit to Seoul, the two countries criticised Japan's departure from its pacifist security doctrine.
Xi, while addressing college students at Seoul National University, said: "In the first half of the 20th century, Japanese militarists barbarously invaded China and Korea, swallowing up Korea and occupying half of the Chinese mainland."
"When the war between China and Japan reached its peak, the Chinese and Koreans helped each other, risking their lives."
Following bilateral talks between the two leaders, they were expected to make a joint statement against Japan, but that did not happen.
Earlier this week, Japan's ruling alliance led by Prime Minister Shinzo Abe ratified a new security policy that allows use of force to help allies who come under attack.
"[Park and Xi] agreed that it is worrying that Japan's attitude toward revising history continues as it even seeks to expand its right to self-defence. The two leaders also agreed that it is regrettable that Japan appears to be attempting to damage and play down the Kono Statement in practice even though it has said it will inherit it," said Ju Chul-ki, senior presidential secretary for foreign affairs.
Park and Xi also called for denuclearisation of the Korean Peninsula.
Noting that bilateral ties between China and South Korea have reached "an unprecedented level of strategic understanding", Park said: "Our two leaders share the view that we must realise North Korea's denuclearisation and resolutely oppose another nuclear test."