US PRESIDENT Barack Obama has started a six-day trip to East and South-east Asia. In Japan, the first stop of his four-nation tour, Mr Obama was forced to adjust to a widening policy conflict over how to cope with a rising China.
The way the two nations deal with their differences on this issue in the coming months could have important implications.
Figuratively speaking, the United States and Japan may be sleeping in the same bed, but they are having different dreams. Mr Obama and Japanese Prime Minister Shinzo Abe cannot let this situation continue.
What exactly is it that divides the two nations? To understand, it is important to be familiar with a commonly accepted view in Tokyo about the current world situation.
With US naval hegemony fading, Japan sees China as moving to fill an emerging power vacuum in East Asia. The business-minded President Obama probably wanted the focus of his visit to be on the ongoing Trans-Pacific Partnership (TPP) deal with Japan in order to score political points ahead of mid-term elections in November. Instead, it was overshadowed by differences about how the two allies should deal with China.
Worried about Chinese claims in the East China Sea, the nationalistic Abe administration has adopted a very confrontational stance. It has also been bolstering the nation's defences in the Nansei island chain that includes Okinawa and the disputed Senkaku/Diaoyu islands. It has even tried to strengthen ties with countries and regions surrounding China, such as India, Mongolia, Russia, South-east Asia and Australia.
For the hawkish Abe government, the current Obama administration is a less reliable ally. This time, Mr Obama merely reiterated at a press conference in Tokyo the US position that the Senkaku Islands are administered by Japan and, therefore, fall within the scope of Article five of the US-Japan security treaty.
Mr Obama said that the US is opposed "to attempts to change the status quo by force". But no high-ranking US official has ever explicitly said "the US will fight with Japan once China occupies the Senkaku islands. We will defend Japan", or any comment to that effect.
The lack of a strong commitment from Washington is deepening Tokyo's suspicions about just how important the security alliance is to the US.
There is a growing scepticism among conservative political circles in Tokyo that the US is gradually bending over backward to appease China. Japanese political leaders are frustrated at the implicit US acceptance of China's intensifying efforts to send patrol ships near the Senkakus on an almost daily basis. US officials have certainly not condemned this latest evidence of China's increased assertiveness.
Some Japanese politicians also believe that Mr Obama's pivot to Asia has more to do with Washington's growing economic interest in China's massive markets, rather than concern about the need for new military deployments.
Earlier this month, US Defence Secretary Chuck Hagel even talked about a "new type of military relations" between China and the US, giving a positive assessment of bilateral military ties when he visited Beijing.
In the eyes of the Japanese, more and more US scholars also appear to have yielded to Chinese power. An article by University of Chicago professor John Mearsheimer entitled "Say Goodbye to Taiwan" in the March-April issue of the National Interest shocked Japanese experts. In it, he wrote that Taiwan will eventually have to give up even its present de facto independent status and seek a Hong Kong-style accommodation with Beijing.
As the examples of Ukraine, Syria and Iran illustrate, the Obama administration has been very reluctant to intervene decisively in world affairs. More and more Japanese are afraid this weak-kneed stance could also apply to the Senkaku Islands issue.
The left-liberal Obama administration, on the other hand, sees Mr Abe's nationalistic behaviour, such as his visit to the controversial Yasukuni Shrine last December, as a security risk. The patriotic act certainly ratcheted up already strained tensions with China and South Korea.
Washington is afraid that Mr Abe's historical revisionism on wartime Japan, combined with Japan's military buildup, will continue to cause needless friction with its neighbours.
On April 22, the Japanese media reported that former Deputy Secretary of State Richard Armitage told Shigeru Ishiba, the secretary general of the Japanese ruling Liberal Democratic Party, that there was no need for Tokyo to rush into reinterpreting the Japanese constitution to allow for the exercise of the right of collective self-defence.
Mr Armitage reportedly said he believed Japan should focus instead on the economy.
Such comments suggest that more US officials may regard Mr Abe a security risk if his nationalist policies lead to further tension with China and South Korea.
This is especially true when the US needs China's leverage and influence, if not support, on other international affairs such as on the Ukraine crisis and North Korea's nuclear and missile programmes.
It is hard to say whether either the US or Japan has a wrong foreign policy. It is natural for any nation to pursue its national interest as top priority. But the two nations do need to agree on how to deal with a rising China.
It is more than a matter of political styles. Many political experts in Tokyo view Japan's nationalistic prime minister and the liberalist US president as finding it difficult to get along on a personal level.
Both nations need to make a concerted effort to engage China rather than contain it. To ease regional tensions, Japan needs to agree with Beijing to shelve the territorial dispute over the Senkakus and try to establish crisis prevention mechanisms, such as hotlines.
Japan may want the US-led alliance to pursue a policy of encirclement against Beijing. But this would benefit only China's military hardliners, which in return could provoke a sharp backlash in Tokyo. Considering the pace of economic development in each country, Japan cannot compete with China in an arms race. Mr Obama appears to realise this, but Mr Abe does not.
And with the reaction of Japan's conservatives in mind, Mr Obama needs to be careful what he says. Speaking in Tokyo yesterday, the US president said that he had not drawn any new "red line" over the Senkaku islands.
Such comments, probably meant to emphasise the need to resolve maritime disputes peacefully, are unlikely to go down well in Japan.
The writer is a Tokyo correspondent for IHS Jane's Defence Weekly.