Chinese President Xi Jinping stressed the joint suffering of China and South Korea under Japanese militarism during a speech in Seoul Friday that came days after Tokyo announced a landmark shift in military policy.
"In the first half of the 20th century, Japanese militarists carried out barbarous wars of aggression against China and Korea, swallowing up Korea and occupying half of the Chinese mainland," Xi said in an address at Seoul National University.
"When the war against Japan was at its highest pitch, the Chinese and Korean people shared their suffering and helped each other with sweat and blood," he added.
Xi's speech came on the second and last day of his state trip to South Korea which had been flagged as a snub to ally North Korea because of his decision to visit Seoul before Pyongyang.
But the key issue of North Korea's nuclear weapons barely got a mention in his address, beyond a passing reference to the need for a "denuclearised Korean peninsula" and the need to resolve all tensions and problems through dialogue.
The hard-hitting language was saved for recalling Japan's repressive colonial rule and wartime aggression -- a message guaranteed to go down well in Seoul.
Relations between Seoul and Tokyo are currently at their lowest ebb for years, mired in disputes related to Japan's 1910-45 rule over the peninsula.
China is also embroiled in a territorial row with Japan and analysts say Xi's efforts to stake out common cause with South Korea reflect a wider diplomatic strategy.
South Korea and Japan are the two key US military allies in the region, and exploiting any rift between them would help China in countering US President Barack Obama's strategic "pivot" to Asia.
- Diplomatic balancing act -
Xi's evocation of Tokyo's military past carried particular resonance in the wake of Prime Minister Shinzo Abe's announcement this week that Japan's powerful military had the right to go into battle in defence of allies.
The shift to a policy of so-called "collective self-defence", marks a highly contentious change in Japan's pacifist stance and was viewed with deep suspicion in Beijing and Seoul.
Xi's courtship of Seoul -- he has now held two summits with President Park Geun-Hye -- leaves South Korea facing a delicate diplomatic balancing act.
The two countries already have strong trade ties, and Seoul wants Beijing to exercise its considerable leverage over Pyongyang to curb North Korea's nuclear ambitions.
But the South's 60-year military alliance with the United States remains the cornerstone of its national defence, and it does not want to become a pawn in the battle between China and the US for influence in Asia.
There are currently around 29,000 US troops stationed in South Korea, which is also protected by the US nuclear umbrella.
Seoul had been hoping that Thursday's summit between Park and Xi would produce a joint statement that carried a clear warning to North Korea over its nuclear ambitions.
But the final text offered little new beyond a reaffirmation of the two sides "firm opposition" to the development of nuclear weapons on the Korean peninsula.
In their remarks to reporters afterwards, Park struck a stronger tone, saying the two leaders had agreed to use "all means possible" to get the North to give up its nuclear bombs.
Xi, by contrast, highlighted an agreement to try to revive moribund six-party talks on North Korea, which Seoul and Washington have made conditional on Pyongyang making a tangible commitment to denuclearisation.