China on Sunday postponed events, scheduled for later this week, marking the 40th anniversary of Sino-Japanese relations in what analysts called "a strong signal" indicating Beijing was adopting a tougher stance.
Two associations - entrusted by the government to organize events to mark the anniversary - cited Japan's attitude over the Diaoyu Islands as the reason for the postponement.
"Considering the current situation", events to commemorate the normalization of relations between the two nations will be "adjusted to an appropriate time", said a statement by the Chinese People's Association for Friendship with Foreign Countries and the China-Japan Friendship Association.
Events were scheduled to take place on Thursday in Beijing to mark the signing of a joint statement between China and Japan on Sept 29, 1972.
But "the atmosphere has been ruined" due to Japan's "buying" of the Diaoyu Islands in the East China Sea earlier this month, the statement said.
Experts said it is necessary for China to keep pressing Japan.
"China should be tough on the territorial issue," said Feng Wei, a specialist on Japanese studies at Fudan University in Shanghai. "China should take this opportunity to push Japan back to the negotiating table."
Wang Ping, an expert on Japanese studies with the Chinese Academy of Social Sciences, said it is not a good time to celebrate the anniversary as the consequences triggered by Tokyo's "islands-purchasing farce" have not ended.
"We have not seen any sincerity by the Japanese government to improve ties," Wang said.
Foreign Ministry spokesman Hong Lei asked Japan on Saturday to immediately stop all acts that harm China's territorial sovereignty after about 30 Japanese police officers landed on the Diaoyu Islands citing, as an excuse, that they were preventing Taiwan activists from landing.
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