http://www.nytimes.com/2010/01/24/world/asia/24japan.html?ref=asia TOKYO — When Defense Secretary Robert M. Gates visited Japan’s new leaders in October, not long after their historic election, he pressed so hard and so publicly for a military base agreement that the Japanese news media labeled him a bully. The difference between that visit and the friendly welcome that a high-level Japanese delegation received just two months later in China, Japan’s historic rival, could not have been more stark. A grinning President Hu Jintao of China took individual photos with more than a hundred visiting Japanese lawmakers, patiently shaking hands with each of them in an impressive display of mass diplomacy. The trip, organized by the powerful secretary general of Japan’s governing Democratic Party, Ichiro Ozawa, was just one sign of a noticeable warming of Japan’s once icy ties with China. It was also an indication that the United States, Japan’s closest ally, may be losing at least some ground in a diplomatic tug-of-war with Beijing. Political experts say Prime Minister Yukio Hatoyama’s greater willingness to engage Beijing and the rest of Asia reflects a broad rethinking of Japan’s role in the region at a time when the United States is showing unmistakable signs of decline. It also reflects a growing awareness here that Japan’s economic future is increasingly tied to China, which has already surpassed the United States as its largest trading partner. “Hatoyama wants to use Asia to offset what he sees as the declining influence of the United States,” said Yoshihide Soeya, director of the Institute of East Asia Studies at Keio University in Tokyo. “He thinks he can play China off the United States.” Mr. Soeya and other analysts say warmer ties with China are not necessarily a bad thing for Washington, which has long worried about Japan’s isolation in the region. But some are concerned that the new openness toward China may also be driven by a simmering resentment within Mr. Hatoyama’s left-leaning government of what some here call the United States’ “occupation mentality.” Those feelings have been stoked by what many Japanese see as the Obama administration’s high-handed treatment in the dispute over the air base on Okinawa. The White House is pressing Japan to follow through on a controversial deal to keep a base on the island that was agreed to by the more conservative Liberal Democrats who lost control to Mr. Hatoyama’s party last summer after decades of almost uninterrupted power. “If we’re worrying that the Japanese are substituting the Chinese for the Americans, then the worse thing you could do is to behave the way that we’re behaving,” said Daniel Sneider, a researcher on Asian security issues at Stanford University. The new emphasis on China comes as Mr. Hatoyama’s government begins a sweeping housecleaning of Japan’s postwar order after his party’s election victory, including challenging the entrenched bureaucracy’s control of diplomatic as well as economic policy. On security matters, the Liberal Democrats clearly tilted toward Washington. Past governments not only embraced Japan’s half-century military alliance with the United States, but also warned of China’s burgeoning power and regularly angered Beijing by trying to whitewash the sordid episodes of Japan’s 1930s-1940s military expansion. American experts say the Obama administration has been slow to realize the extent of the change in Japan’s thinking about its traditional protector and its traditional rival. Indeed, political experts and former diplomats say China has appeared more adept at handling Japan’s new leaders than the Obama administration has been. And former diplomats here warn that Beijing’s leaders are seizing on the momentous political changes in Tokyo as a chance to improve ties with Japan — and possibly drive a wedge between the United States and Japan. “This has been a golden opportunity for China,” said Kunihiko Miyake, a former high-ranking Japanese diplomat who was stationed in Beijing. “The Chinese are showing a friendlier face than Washington to counterbalance U.S. influence, if not separate Japan from the U.S.” Some conservative Japan experts in Washington have even warned of a more independent Tokyo becoming reluctant to support the United States in a future confrontation with China over such issues as Taiwan, or even to continue hosting the some 50,000 American military personnel now based in Japan. Despite such hand-wringing among Japan experts in the United States, Mr. Hatoyama continues to emphasize that the alliance with Washington remains the cornerstone of Japanese security. And suspicions about China run deep here, as does resentment over Japan’s losing its supremacy in Asia, making a significant shift in loyalty or foreign policy unlikely anytime soon, analysts say. But in the four months since Mr. Hatoyama took office, there has been an unusual flurry of visits back and forth by top-ranking Chinese and Japanese officials, including one last month to Tokyo by China’s heir apparent, Vice President Xi Jinping. The new mood of reconciliation is also evident in the novel ideas that have been floated recently to overcome the differences over wartime history that have long isolated Japan from the region. These include a recent report in the Yomiuri Shimbun, a Japanese newspaper, based on unidentified diplomatic sources, of a Chinese initiative for reconciliation that would include a visit by Mr. Hatoyama to Nanjing to apologize for the 1937 massacre of Chinese civilians there by invading Japanese soldiers. President Hu would then visit Hiroshima to proclaim China’s peaceful intentions. While both countries dismissed the report as speculation, it spurred wide talk here that the report might be a trial balloon by one of the two countries that could signal a new willingness to make some sort of diplomatic breakthrough on the history issues. And a week after the visit to Beijing by Mr. Ozawa and his parliamentary delegation, which Mr. Hu heralded as the start of a smoother era in Japan-China relations, Tokyo reciprocated with its own display of eager hospitality during a visit to Tokyo by Mr. Xi, the Chinese vice president. Mr. Hatoyama arranged a meeting between Mr. Xi and Emperor Akihito at the Imperial Palace in Tokyo on short notice, breaking protocol that such audiences be arranged more than a month in advance. Mr. Ozawa, a shadowy kingmaker whose power rivals Mr. Hatoyama’s, is said to have warm feelings for China, where he has often visited, and he is widely seen as the force behind Japan’s latest overtures to Beijing. Other members of Mr. Hatoyama’s cabinet remain less convinced that any drift away from the United States is a good idea. One of the skeptics is Defense Minister Toshimi Kitazawa, who has stressed the need for the American military presence to offset China and a nuclear-armed North Korea. Last month, Mr. Kitazawa brought in Yukio Okamoto, a widely respected former diplomat and adviser to Liberal Democratic prime ministers, to advise Mr. Hatoyama on security issues. “The Democrats have to realize the threat we have on the Korean Peninsula, and that China is not a friendly country in military matters,” Mr. Okamoto said. Mr. Soeya, of Keio University, warned that the new Japanese government should at least think hard before sidling closer to China, saying, “Mr. Hatoyama does not have a clear sense of what relying on China would really mean, or whether it is even actually desirable.