China is an emerging superpower. The United States is the incumbent. The potential for destructive clashes between the two giants seems potentially unbounded. Yet the two are also intimately intertwined. If they fail to maintain reasonably cooperative relationships they have the capacity to wreak havoc not only upon each other, but also upon the entire world.
China is a rival of the US on two dimensions: power and ideology. This combination of attributes might remind one of the clash with the Axis powers during World War II or the Cold War against the Soviet Union. China is of course very different. But it is also potentially far more potent.