It appears to be the season for diplomatic resets in Asia. Would-be hegemon China is at the centre of this regional spring thaw. India is not the only rival with which Beijing has recently been trading pleasantries rather than threats. Usually fraught China-Japan ties are in the midst of an upswing as well. Last week, Chinese Premier Li Keqiang was in Japan on a three-day state visit, his first trip to Tokyo since taking office five years ago. It was also the first top-level bilateral visit after relations between the two countries plummeted in 2012 over a chain of disputed islands claimed by both sides. The melt in this years-long freeze has been evident for several months. One signal came last September when Prime Minister Shinzo Abe became the first Japanese leader in 15 years to attend the Chinese Embassy’s annual National Day celebrations in Tokyo. Since then, Mr. Abe and Mr. Xi have met on the sidelines of an Asia-Pacific Economic Cooperation summit in Vietnam. But the real “reset” began in more recent weeks with the resumption of a stalled high-level economic dialogue after an eight-year hiatus, which followed close on the heels of an April visit to Tokyo by China’s State Councillor and Foreign Minister Wang Yi. In early May, Mr. Abe spoke to Mr. Xi on the phone to discuss the unfolding events on the Korean peninsula, the first phone call ever between the two leaders. Talk of a possible trip to China by Mr. Abe later this year is rife. However, it would be sensible to hold back on the champagne just yet.

Japan and China have one of the most tense, yet economically intertwined relationships. Beijing believes Japan is yet to properly atone for its brutal invasion of China in the run-up to and during the Second World War. In the post-War alignment Japan has remained firmly tethered to the U.S., often putting it in an adversarial position vis-à-vis China. Perhaps the most challenging point of contention is the territorial dispute over the Diaoyu/Senkaku islands as they are known in China and Japan, respectively, in the East China Sea. Nonetheless, Japan was an important player in China’s economic rise, which saw the country’s transformation from an agrarian backwater to a global manufacturing powerhouse. According to the Japan External Trade Organisation, China-Japan trade stands at about $350 billion (by comparison, India-China trade is $84.44 billion). China has overtaken Japan as the world’s second largest economy and has also eclipsed it as a global geostrategic player. And the two countries continue to vie for influence in the region, with Southeast Asia in particular emerging as a theatre for this competition.

So, what explains the ongoing thaw, which has seen Mr. Li chatting with Japanese emperor Akihito and gifting the archipelago a pair of crested ibises? According to Shin Kawashima, a China scholar at the University of Tokyo, there is a triumvirate of motivating factors on the Japanese side: an unpredictable U.S., North Korea and business interests. U.S. President Donald Trump’s America First policy and the tariffs he has slapped on some $60 billion worth of Chinese products have also impacted Japan, which despite its status as a U.S. ally, failed to get any exemption from new duties on steel and aluminium. This is only the latest example of the increasingly uncertain U.S. policy towards Japan and the wider region, which Prof. Shin describes as “fragile and vague”. The result is that Japan needs to keep ties with China on an even keel, at least until it can be more sure of the U.S.’s intentions. Mr. Abe is also hoping that China can use its influence with North Korea to highlight Japan’s concerns, at a time when Tokyo feels somewhat shut out of the flurry of diplomacy on the Korean peninsula. He is particularly worried that in the heat of rapprochement, allies like the U.S. will forget about the 12 Japanese citizens abducted by North Korea in the 1970s and '80s who still remain unaccounted for. And finally the many Japanese businesses invested in China, that have on occasion suffered punitive measures from Beijing, always welcome stronger bilateral ties.

Conversely for China, the idea of Japan’s leader asking for support on North Korea plays well domestically as an example of Beijing’s international clout. Moreover, given the simmering possibility of a trade war with the U.S., better ties with economic heavyweight Japan are also in China’s interests. In addition, China is keen on getting Japan to play ball with its signature Belt and Road Initiative (BRI), something that Mr. Li stressed more than once during his visit last week. His efforts culminated in the establishment of a public-private council in Japan to discuss joint projects with China related to the BRI. Although initially reluctant to participate in the BRI, Tokyo has signalled that it is open to the initiative as long as proposed infrastructure projects meet the criteria of being “open, transparent, fair and economically feasible.” In this way Japan can keep on the right side of China without necessarily committing to participation. Similarly, the Japan-backed Asian Development Bank is exploring co-financing projects with the Beijing-led Asian Infrastructure Investment bank, even though Japan has formally steered clear of it.

Yet, any China-Japan alignment is a tactical and provisional affair, rather than long-term and strategic, born out of the current moment in a fluid geopolitical landscape. And as with the India-China reset, although it is temporarily beneficial to both sides, the foundation of the bilateral relationship remains troubled and treacherous.