Mr Rumsfeld was addressing an audience of ministers, senior defence officials and security experts from 20 nations at the Shangri-La Dialogue - one of two informal security gatherings held in Southeast Asia over the past week.
The future of Northeast Asia was the topic on everyone's lips, both in the public speeches and in the backroom discussions. In the longer term, many were asking how to create a new security body to ease tensions in a region where the rise of China and the militarisation of Japan are shattering long-held strategic assumptions. But in the short term, it is the diplomatic tussle over the Japanese leadership's visits to the Yasukuni war shrine in Tokyo that creaks like a fault line into the heart of the wider issues.
A dispute over shrine visits and China's reluctance to acknowledge Tokyo's post-1945 peace policy are crippling relations, writes chief Asia correspondent Greg Torode
US Defence Secretary Donald Rumsfeld has been at his most pugnacious during his rare swing through Southeast Asia in the past week. In one Singapore address he called Iran the world's "leading terrorist nation" and bluntly warned Russia against "constraining the freedom of its neighbours". But when it came to the strained ties between China and Japan, Mr Rumsfeld was far more diplomatic. "Let me walk around it rather than confront it," he said with a smile.
"There's a lot of history there. And sometimes it takes time to put pieces of history behind us," he said. "And it is in nobody's interest, in my view, for those two countries to have a relationship on any basis other than a civil, constructive, mutually beneficial relationship."
Mr Rumsfeld was addressing an audience of ministers, senior defence officials and security experts from 20 nations at the Shangri-La Dialogue - one of two informal security gatherings held in Southeast Asia over the past week.
The future of Northeast Asia was the topic on everyone's lips, both in the public speeches and in the backroom discussions. In the longer term, many were asking how to create a new security body to ease tensions in a region where the rise of China and the militarisation of Japan are shattering long-held strategic assumptions. But in the short term, it is the diplomatic tussle over the Japanese leadership's visits to the Yasukuni war shrine in Tokyo that creaks like a fault line into the heart of the wider issues.
"Nothing is going to happen on any new security architecture until the Yasukuni issue is put behind us," one Asian diplomat said. "That seems to be the bottom line. You don't get far plotting the big picture stuff when you can't even get the leaders around a table now."
Not everyone was as diplomatic as Mr Rumsfeld, who was seeking to soothe an old ally - Japan - and not dent an evolving but complex relationship with China.
In private, US officials have said Japanese leaders have been told by Washington that their repeated shrine visits are not helping anyone in Northeast Asia, not least themselves.
South Korean officials yet again forcefully raised the issue with Japanese counterparts in one bilateral meeting in Singapore. More informally, Chinese and Japanese academics went head to head in several public forums, proxy warriors for habitually cautious diplomats.
The good news is that signs of a possible easing of tensions are starting to emerge. Both sides, however, are going to have to play their part in a solution, the week's discussions suggest.
Japanese Prime Minister Junichiro Koizumi is standing down as head of the Liberal Democratic Party in September, effectively removing himself from power.
Mr Koizumi's decision to visit the shrine annually since taking power in 2001 has thrust the issue onto the diplomatic stage - despite the fact that he insists the visits are to renew Japan's pacifist pledge by praying for all Japanese war dead. Yasukuni enshrines all of Japan's 2.5 million war dead, including 14 Class A war criminals tried and convicted at the end of the second world war.
Chief Cabinet Secretary Shinzo Abe, the man considered the frontrunner to replace Mr Koizumi, has long been an enthusiastic shrine visitor. But as the race intensifies, he has said he does not want it to become a political issue. He has, however, yet to rule out a visit in September, the anniversary of the Japanese surrender.
Former prime minister Yoshiro Mori, a political patron of Mr Abe as head of the so-called Mori faction, last week urged any new leader to stay away from the shrine. "It is important to improve relations with South Korea and China," Mr Mori said, music to the ears of Japan's powerful business lobbies.
Chinese academic Zhou Xingbao captured the mood during the 20th Asia Pacific Roundtable on security issues in Kuala Lumpur last week. "The ball is now on the Japanese side of the court," Mr Zhou said. "It is up to the Japanese leaders now."
Mr Zhou, senior research fellow at the Chinese Institute of International Studies, said the Japanese leaders had created a major obstacle, but insisted a lasting friendship still remained.
"There has always been a good- neighbourliness," he said. He described the relationship as "a long- standing, traditional friendship that will not be easily broken". He pointed to a growing economic relationship and expanding exchanges between Japanese and Chinese people. "It is important to note that such exchanges have never stopped," he said.
Even as the tensions reached their height in the past year, so trade continued to grow. Like several academics, he noted that China has in the past year become both South Korea's and Japan's biggest trading partner.
His Japanese counterpart, retired ambassador Koji Watanabe, said that he believed the issue would be resolved, normality restored and economic integration sustained. He did, however, urge China to look at itself as well.
Mr Watanabe spoke with a touch of bitterness that China was wilfully ignoring Japan's peaceful post-second world war development; that China's intervention had stopped Japan becoming a permanent member of the UN Security Council.
He quoted Mr Koizumi as saying Japan's post-war pacifist history represented "six decades of remorse".
"This has never registered on the minds of the Chinese," said Mr Watanabe, a senior fellow at the Japan Centre for International Exchange. "China is forcing psychological reassessments by Japanese people, and that is never easy."
He said China's deepening relationships with India, Russia, South Korea and the whole of Southeast Asia cast Japan as the odd one out. "The antipathy between the peoples of Japan and Southeast Asia has never been as pronounced as it is now," he said.
Sitting between them was respected German political scientist Karl Kaiser, a visiting scholar at Harvard University's John F. Kennedy School of Government.
Softly spoken, Mr Kaiser nonetheless delivered strong messages to both Beijing and Tokyo from the intriguing perspective of a German who has lived through and studied his nation's reconciliation with Europe. He spoke of the paradox as the rise of historical debate pushed the countries apart. "They have today simultaneously reached the highest degree of economic interdependence and the worst state of mutual perception and distrust since the establishment of diplomatic relations in 1972," he said.
"A European observer has the impression that these two great countries, which have given so much positive input to each other ... are on a path that can lead to very serious conflict.
"Conversely, given their enormous relevance to Asia and indeed to global politics, they have a shared responsibility and ... could set in motion a process that would benefit the entire region."
To Mr Watanabe, he spoke of repeated official expressions of sorrow and forgiveness - including by the emperor - struggling to take root in the wider society and political culture. "The credibility of these acts was seriously undermined by the demonstrative visits of Koizumi to the Yasukuni Shrine," Mr Kaiser said.
He said that Japan was paying a high price for not facing up to its past properly. That had hurt its essential national interests, such as the quest for UN Security Council membership.
Mr Kaiser also voiced concern at the lack of distinction between those who committed atrocities and crimes and the nation they came from. Successive political leaders in Europe had generally worked to liberate younger generations from stereotyping.
"A failure to distinguish can be observed in East Asia," he said, outlining a risk of "mutually reinforcing nationalism". "China uses Japan's wartime atrocities to denigrate modern Japan as a whole, pushing into the background its post-war record of establishing a successful democracy, of conducting a peaceful and constructive foreign policy and providing for East Asian regionalism through its aid and investment policies."
He noted that positive acts had been ignored by China and "every voice or act of extremism is almost eagerly picked up and considered representative of the other country". He leavened such a bleak outlook by urging action to jointly review school history books and strengthen diplomatic and security ties. He urged Japan to find an alternative way of remembering the dead than prime ministerial visits to Yasukuni.
The issue of the shrine and Beijing's refusal to host Mr Koizumi in a summit meeting meant the two sides were currently painted into a corner.
The prospect of a successor to Mr Koizumi offered a fresh start, he said.
The moment for bold measures, it seems, has arrived.
