Ill will between Japan and South Korea a strategic problem for US The US is becoming increasingly concerned about the deteriorating ties between its two north Asian allies and security partners, Japan and South Korea, amid its tussle for power in the region with China. Japan's Shinzo Abe and Park Geun-hye have not held a formal meeting since the South Korean president was elected in February because of Seoul's unhappiness at what it regards as Tokyo's insufficient remorse regarding its colonial rule over its neighbour. Ahead of her trip to Europe this month, Mrs Park added fuel to the controversy by expressing her openness to talks with North Korea, while describing a summit with Japan as "pointless." The Japanese government, in turn, is frustrated and angry about what it regards as Seoul's refusal to even discuss the issue or countenance measures to reduce the rising diplomatic tensions. "This has now emerged as the biggest strategic challenge to American interests in Asia," said Kurt Campbell, who served as the State Department's top diplomat for Asia in US President Barack Obama's first term. Beijing has been happy to needle Tokyo along the way, with the Foreign Ministry this week calling Ahn Jung-geun, a Korean independence activist who assassinated a Japanese leader in 1909, "a respected figure" in China. The tensions over history between Tokyo and Seoul are longstanding, with tempers flaring regularly when Japanese politicians visit Yasukuni Shrine in the capital, which honours convicted war criminals. Seoul points to a series of recent incidents, including Mr Abe's questioning in last year's election campaign on whether Japan "invaded" its former colonies; a ministerial visit to Yasukuni in May and the Osaka mayor's suggestion that Tokyo's enforced wartime prostitution was "necessary." Park Joon-yong, director for northeast Asian affairs at South Korea's foreign ministry, said Seoul regarded the Japan relationship as "very important." "We are partners who should contribute to peace and prosperity in the region and in the world," he said. But recently, among Japanese politicians, there have been a lot of remarks and actions based on historical revisionism. Senior White House officials said Washington is "concerned" about the two countries" poor relations but could not mediate between them. "We want to create the conditions where both sides can find a solution to this," an official said. The breakdown in relations has stunted US efforts to consolidate its strategic presence in east Asia, evidenced by Seoul's last-minute rejection in 2012 of a military co-operation pact with Japan, which had been brokered by the US. But while South Korean officials are aware of US dismay at the breakdown in Seoul-Tokyo relations, they are adamant that the onus lies on Japan to address its "incorrect" position. Japan has fallen back on time-tested formulas about the issue of its colonial rule being settled, and now complains of "Korea fatigue" because of what it regards as Seoul's continual playing up of history. White House officials point out that despite the problems, the US, Japan and South Korea have continued to co-ordinate on policy for North Korea and conducted joint military drills in October. However, former US government officials say Japan-South Korea tensions threaten to undermine US efforts to consolidate its regional influence at a time when China is flexing its muscles. "Two allies not co-operating increase our military risk," said Joseph Nye, of Harvard University, and a former Clinton administration official, referring to North Korea. Richard Armitage, a former senior official in the Pentagon and State Department in Republican administrations, believes the main issue for Seoul is Japanese statements on the so-called "comfort women" forced to work as prostitutes in the war. "It is Mrs Park's view that, how can she have a summit when she might be embarrassed a week later by some stupid statement from a Japanese politician," he said. The last summit between the two countries" then leaders, in December 2011, was overshadowed by a disagreement between Lee Myung-bak and Yoshihiko Noda over the need for Japan to make fuller amends for the "comfort women" system. A September poll by the Asan Institute for Policy Studies found that 62 per cent of South Koreans regarded Japan as a military threat, while respondents - asked to rank their sentiments towards Japan on a scale of 1 to 10 - gave an average score of 2.7. For North Korea, the equivalent figures were 70 per cent and 2.4. While Washington might hope for a more conciliatory position from Seoul, pressure for a rethink risks inflaming lingering resentment towards the US over the Dokdo islands claimed by both Seoul and Tokyo. Sovereignty over the islands, known as Takeshima, was left unresolved by the 1951 San Francisco peace treaty that ended second world war in the Pacific. "The US is not just a bystander in this - the state of Dokdo was left in a grey area deliberately," says Chung Jae-ho, a professor at Seoul National University. Park Geun-hye is just asking Japan to be reasonable. The US itself has faced questions about its commitment to Asia, a perception Susan Rice, the national security adviser, tried to combat in a speech in Washington on Wednesday about the region. "The United States of America will be there, reliable, constant, strong and steady, for the long term," she said.