As US President Barack Obama meets China's leaders in Beijing, the two countries' relationship appears to be that of established superpower and emerging giant.
But how far and how fast does China have to grow to match the United States' economic and military might?
The US has built up a massive trade deficit with China. The US argues that this is partly because China has kept its currency artificially weak, which makes its products cheaper overseas.
Until the 1990s, the US economy grew strongly while China remained relatively stagnant. Since then, and especially since the turn of the millennium, China's growth rate has surged, driven by economic reforms, a huge workforce and massive investment.
US military spending continues to dwarf all other countries.
Getting an accurate assessment of China's military capabilities is difficult, analysts say, because the official defence budget is almost certainly far lower than actual spending.
But the People's Liberation Army - at almost 1.25 million strong - remains the world's largest. Its budget has grown rapidly as the military modernises and invests in more high-tech weapons systems.
China's huge population gives the country's economy a vast workforce from which to draw.
Thirty years ago, the "one child policy" was introduced in cities to limit the size of families, and this was reaffirmed recently when the population reached 1.3 billion.
One result of the recent economic boom has been a growing middle class, demanding a higher standard of living based on perceived Western standards.
Analysts predict this is likely to further stretch already limited food, water and other natural resources.