Japan on Thursday called for “constructive and stable” ties with China as both sides marked 50 years since ties normalized, albeit with little public fanfare.

Growing frictions over China’s military might and regional saber-rattling have left Beijing-Tokyo relations chilly, and there has been no major diplomatic ceremony to mark the anniversary.

Instead, messages from Japanese Prime Minister Fumio Kishida and Chinese President Xi Jinping were read at an event in Tokyo supported by the government and Chinese embassy and hosted by powerful business lobby Keidanren.

In his message, Kishida, who was not present at the event, warned that relations with China “although they have various opportunities, face many challenges and problems.”

“I wish to build constructive and stable Japan-China relations for the peace and prosperity of not only our two nations but also the region and the world,” he said.

Xi said in his message that ties are of “great importance,” adding that he is willing to work with Kishida to use the anniversary as an “opportunity.”

The countries should “work together to build a China-Japan relationship that meets the demands of the new era,” he added.

The world’s second- and third-largest economies are major trading partners and just a few years ago seemed poised for a diplomatic blossoming, with plans for a state visit by Xi.

Since then, relations have deteriorated significantly as Beijing strengthens its military, projects its power regionally and beyond, and takes a harder line in disputed territory.

In recent months, Japan has assumed Chinese missiles have fallen into its exclusive economic zone, and Tokyo has protested what it describes as mounting air and sea injuries.

Japan also regularly complains about Chinese activity around the disputed Tokyo-controlled Senkaku Islands, which Beijing claims and which Diaoyus calls.

The war in Ukraine has only deepened the rift, with Japan backing Western allies opposed to the Russian invasion while Beijing avoids criticizing Moscow.

Japan’s brutal occupation of parts of China before and during World War II also remains a sore point, with Beijing accusing Tokyo of failing to atone for its past.

Despite all the tensions, the two countries remain economically intertwined: China is Japan’s largest trading partner and Japan is China’s second largest after the United States.

And there have been reports that Xi and Kishida could hold talks online or in person in the coming months.