TOKYO/BEIJING -- As Japan and China mark the 45th anniversary of their bilateral peace and friendship treaty, friction over the Fukushima nuclear plant wastewater release and Beijing's detention of a Japanese national has cast a cloud over the occasion.

The leaders of both countries did not attend events Monday commemorating the landmark pact that went into effect in 1978, six years after the two countries normalized relations. Instead, Japanese Prime Minister Fumio Kishida and Chinese Premier Li Qiang exchanged congratulatory messages.