China's globetrotting president and premier have visited many countries to cement Beijing's growing influence. Japan has been a glaring omission. This is not just because she does not have the oil and other natural resources that lubricate China's developing ties with other nations. There are more important bilateral, regional and global reasons why regular top-level contact between the two Asian giants should take precedence. The reason it does not is differences that prevent the parties to one of the world's most important relationships from moving on. This is an impediment to regional harmony and stability that seems likely to get worse before it gets better. The latest spark to ignite tension between the two countries is a case in point. It is Tokyo's plan to lodge a protest with Beijing after China's largest offshore oil developer was reported to have entered full production at an undersea oilfield in the East China Sea, to which both sides lay claim. The move comes hard on the heels of China's official expression of concern over reports that Japanese Chief Cabinet Secretary Shinzo Abe visited the controversial Yasukuni Shrine to the country's war dead in Tokyo in April. These aggravations of a troubled relationship are ill-timed. Amid regional tensions heightened by North Korea's defiant missile tests over the Sea of Japan, or East Sea, and stalled talks on its nuclear programme, the lack of top-level contact between China and Japan is unhelpful. All eyes are now on Japanese Prime Minister Junichiro Koizumi in the lead-up to August 15, the anniversary of Japan's surrender in the second world war. Mr Koizumi, an unrepentant worshipper at the shrine, has so far stopped short of the provocation of visiting it on that date. But he has been cagey about his plans this year, the last opportunity before he steps down from office next month. Though he will soon depart the scene, a visit to the shrine by Mr Koizumi on the anniversary would be a fresh blow to hopes of improved relations. Moreover, Mr Abe, the frontrunner to succeed him, is a staunch defender of the visits. Beijing has ruled out a summit between the two nations so long as Japan's leaders worship at a shrine that honours 14 class-A war criminals among the nation's war dead. It is welcome news, therefore, that Minister for Foreign Affairs Taro Aso, also a leading contender to succeed Mr Koizumi, is to distance himself from Mr Abe. To mend damage to relations with both China and South Korea over the shrine issue, he is expected to unveil on Tuesday a plan to make the Shinto shrine a national war memorial and to determine the people to be honoured. This would pave the way to separate class-A war criminals. Politically, it is an attempt to tap into the lukewarm sentiment among most Japanese towards the shrine visits. Both the shrine and the East China Sea issues serve as flashpoints on a wider canvas marked by mutual suspicion and a sense that China's rise is challenging the political, economic and security assumptions that have governed the region for decades. Both capitals have to work harder to see that short-term tensions do not become a long-term quagmire. The leadership role that can be played by China and Japan in their own northeast Asian neighbourhood, across Southeast Asia and beyond, cannot be overestimated. Beijing and Tokyo have the potential jointly to project East Asia on to the world stage as never before. Visits to Yasukuni by Japanese prime ministers are far from a political imperative, as evidenced by a continuing debate in Japan. Beijing is well aware of this. Hence President Hu Jintao's offer this year to meet Mr Koizumi if he stopped his shrine visits, which was pitched at a wider public audience. It is Japanese politicians who will have to shift ground on an issue on which Beijing will not budge. Mr Aso's plan is at least a step in the right direction.