Tokyo and Beijing have agreed to introduce a hotline system to prevent accidental clashes in the East China Sea from escalating into more serious confrontations, the latest indication that the two governments are looking to forge a less confrontational relationship.      

Critics warn, however, the underlying hostility that has dogged bilateral relations for decades will not evaporate overnight. And those often fraught links will once again be tested this week when China marks the 80th anniversary of the Nanjing Massacre.

December 13 marks the fall in 1937 of the former Chinese capital of Nanjing, a defeat that was followed by six weeks of atrocities - including massacres and rapes - perpetrated by the Imperial Japanese Army against the city's civilian inhabitants. Some historians put the number of deaths as high as 300,000, although there are conservatives in Japan who insist that there is no evidence of any atrocities and that there were no deaths at the hands of the Japanese military. Reports of atrocities, they insist, have been fabricated by the Chinese.

Chinese red-letter day

The anniversary is very much a red-letter day on the Chinese calendar and will be marked in Nanjing and Beijing, although analysts suggest the ceremonies may be slightly more understated than they have been in the past due to the improving relations.

The agreement on the hotline was reached during discussions between senior government officials in Shanghai in early December, more than a decade after the suggestion was first proposed. It has taken 10 years to reach a deal because of the dispute over the Diaoyu or Senkaku Islands, an archipelago of uninhabited islands in the East China Sea that Japan presently controls, but China claims sovereignty over.

The deal has only now been agreed upon because the hotline plan makes no mention of the territorial row.

Read more: Japan's new security role

"Obviously this is a positive development, but it is far too early to say that the two sides have buried the hatchet," said Garren Mulloy, a defense expert and an associate professor of international relations at Japan's Daito Bunka University.

"This agreement will allow both sides to gain more control of any situation that might crop up," Mulloy told DW, pointing to the incident in January 2013 when a Chinese frigate locked its weapons fire control radar onto a Japanese destroyer and an airborne helicopter in a tense encounter in the East China Sea.

"The Japanese commander did not respond in kind, which is fortunate, but a hotline should be in place to prevent just that kind of situation from rapidly getting out of hand," Mulloy said.

Bilateral breakthrough

The breakthrough in bilateral ties can arguably be traced back to November, when Japanese Prime Minister Shinzo Abe and Chinese President Xi Jinping emerged from talks on the fringes of the Asia-Pacific Economic Cooperation (APEC) summit in the Vietnamese city of Danang to declare that the two nations were to embark upon a "fresh start" to the relationship.

Abe and Xi announced that the hotline mechanism would be set up, that they would seek a shared solution to the problems posed by a belligerent regime in North Korea and that they would arrange a three-way summit with South Korea's leadership in the near future.

Smiling broadly as he shook the Chinese leader's hand for the cameras, Abe said, "At the end of the meeting, President Xi said this is a meeting that marks a fresh start in relations between Japan and China. I completely feel the same way."

In Manila just two days later, Abe went one step further and claimed that relations between Tokyo and Beijing have improved to the point that the two leaders may visit each other's capitals as soon as next year.

Since then, Abe has expressed his support for China's ambitious "One Belt, One Road" economic development plan that would link the Far East with the Middle East, Africa and Europe.

Wariness on China

Yet there are those in Japan who caution wariness when dealing with China on the grounds that Beijing has an aggressive expansion agenda and that it is playing its cards very closely to its chest.

"An agreement on a maritime hotline is desirable for both sides, but I do not believe that we can say that things are generally rosy in the relationship with China," said Yoichi Shimada, a professor of international relations at Fukui Prefectural University.

"But China is retaining the upper hand in every aspect of the 'One Belt, One Road' scheme and I believe that bureaucrats at Japan's Foreign Ministry are far too appeasement-oriented," he said.

"We have to remember that Xi and other senior members of the Chinese Communist Party have quite openly stated that their intention is to become the hegemonic power in the Asia-Pacific region and that they will not be content with cooperative relations with Japan and other countries in the region," he said.

"As China becomes more and more economically and militarily powerful in the future, all the nations in the region must understand that it wants hegemonic power," he said. "And that is one reason why Japan must retain the military capability to defend itself."