Over the next few days, those broadening and deepening relations between Beijing and Washington will be in the spotlight as China forms the centrepiece of his six day swing through the region. But, amid the blizzard of punditry and canned warmth of tightly choreographed diplomatic theatre, the remarks at the very start of Obama's jaunt should not be forgotten.

They certainly will not be across the region, both inside and outside China.

'The United States will strengthen our alliances, build new partnerships and we will be part of multilateral efforts and regional institutions that advance regional security and prosperity,' Obama said shortly after touching down in Tokyo, where he would go on to reach out to both Japan and China in his first major speech on Asia.

'The alliance between the United States and Japan is a foundation for security and prosperity, not just for our two countries, but for the Asia-Pacific region,' he said.

Given all the hot talk of difficulties in the alliance that has been the cornerstone of Washington's projection of power across Asia for decades, the bedrock that relationship is apparently built on is worth noting.

The historic victory of the Democratic Party of Japan (DPJ) in August polls to shatter the conservative Liberal Democratic Party's six-decade grip on power has created fresh challenges and uncertainties, from the future of the US presence on Okinawa to Japan's own regional visions.

But some seasoned observers are stressing that the core relationship remains rock solid. Ralph Cossa, president of the Centre for Strategic and International Studies' Pacific Forum, noted that the DPJ may be trying to distinguish itself from its predecessors by demanding a more 'equal' relationship with Washington but has repeatedly asserted the importance of the US alliance in keeping Japan secure.

He also described as 'ridiculous' theories that Japan was tilting towards China at the expense of the US. In fact Washington welcomed Prime Minister Yukio Hatoyama's attempts to improve Sino-Japanese ties. 'No one there loses sleep over Tokyo moving too close to Beijing; the concern is always over a failure by either or both sides to manage the natural tensions that will limit how close the two can actually become,' he said.

Initial assessments of his speech on Saturday, in which he reached out to both Japan and China, playing down the perceived threats of China's rise, have been largely positive. It is, of course, a rhetorical tightrope Obama has been approaching since the earliest days of his candidacy. Throughout, he has promised to continue his predecessors' work to improve ties while not ducking differences with China and the challenges facing Sino-US ties.

He has consistently stressed the importance of the alliances with Japan and South Korea, and of building new friends across Southeast Asia.

On a practical level, however, the complexity of that position is becoming ever more apparent as an increasing number of US agencies find themselves dealing with China. Whether it is intelligence-related issues, free trade or regional security, China is both part of the problem, and part of the solution.

And because of those harsh realities, the region is looking beyond Obama's words, to his actions. How hard will he push China on its continuing human rights abuses, both during his trip and later, for example?

As Taiwanese political scientist Dr Lo Chih-cheng told The Associated Press, 'Obama must not simply say 'yes' to China, but rather say 'no' when he needs to.'

Such an approach is likely to help another plank of Obama's East Asian enterprise - restoring and developing ties across the 10 nations of South- east Asia.

Talking privately to envoys across that region it is clear many are looking for the US to play a greater role again, in large part to balance China's own highly successful diplomacy in recent years.

Some, such as Vietnam and the Philippines, have felt the harder edge behind China's soft power in recent years. Others, too, are finding they are experiencing the same challenges as the US, in a smaller way, in expanding ties with Beijing.

In that regard, both Washington and the region were hot for yesterday's inaugural summit between Obama and his counterparts from the Association of Southeast Asian Nations.

It is a reminder that, on some levels at least, China's rise is an opportunity for the US when it comes to getting close to the rest of East Asia.

One of the core moments in his address in Tokyo came with the line: 'The United States does not seek to contain China, nor does a deeper relationship with China mean a weakening of our bilateral alliances.

'On the contrary, the rise of a strong and prosperous China can be a source of strength for the community of nations.'

It is a phrase pregnant with meaning, suggesting issues far too sensitive to be raised in the rhetorical confines of presidential sound bites.

It is a statement of hope as well as intent - and a reminder that Obama's approach to an ever more complicated East Asia remains an early work in progress.