By Jonathan Marcus
BBC diplomatic correspondent
China is not the first stop on President George Bush's itinerary.
China's rapid growth is changing the balance of power in Asia
But China's rise is the issue that will be in the forefront of people's minds at each and every one of his stops on a tour that takes in Japan, Korea, an Asia-Pacific summit, China and finally Mongolia.
China's emergence, not just as a regional but also as a global economic player, is changing the diplomatic landscape in Asia.
China's diplomacy - often linked to the quest for raw materials - now extends into Africa, into the Caucasus and even Latin America.
But it is in Asia that the most immediate effects are being felt. And China's economic rise is being accompanied by concerns in some quarters about its developing political clout and longer-term fears about its military power.
Diplomacy tends to be presented as a zero-sum game - if one side is rising then another country's power must be waning. And a sense that US power in the region is in decline is part of the complex package of perceptions that President Bush will be trying to dispel.
The Pentagon sees China's military build-up as a threat
In part, the Americans have themselves to blame for this perception.
Secretary of State Condoleezza Rice failed to attend an important Asean meeting. And the Americans have sought to use successive Asia Pacific Economic Co-operation (Apec) summits to push their agenda of security and counter-terrorism - issues which are less central to other Asian actors.
There is a growing impatience, a feeling that Washington is not sufficiently engaged with the rest of the region's agenda.
Part of the problem is that the policy options facing the Americans are complex.
Security matters still loom large, notably the continuing controversy over North Korea's nuclear programme.
China's military modernisation is also sounding (possibly premature) alarm bells in the Pentagon.
And regional tensions between China and Japan and between Japan and South Korea - frictions that hark back in one way or another to Japan's war-time behaviour and its legacy - make Washington's task even harder.
Indeed these rows, which appear to be about the past, are often much more about the present - about who is going to emerge as regional top-dog.
A problem too is that on China, as in so many other areas of US foreign policy, opinion in Washington is divided.
Some Republicans want to pressure China on human rights issues while others - the more business-orientated - want to pursue an active engagement.
The dichotomy in US policy has been neatly described as a struggle between "panda huggers" and "dragon slayers".
The difficulty is not just in framing policy but in finding language to describe it.
"Managing China's rise" sounds patronising and affords the US an ability to shape China's destiny which it simply does not have. "Containing China" hankers back to Cold War terminology which is equally unhelpful.
Reconciling these tensions is Mr Bush's task. He hopes to demonstrate on this trip that despite the problems of Middle East peace or of security in Iraq, and irrespective of the so-called global war on terror, Asia matters.
And it looks set to matter more and more if China proceeds along its present economic trajectory.