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The question is what could actually cause the United States to fight China. What if China invades and occupies Taiwan, a democratic U.S. partner and arms customer? Would America actually risk World War III? What if China forces its claim to the Senkaku Islands, which the United States considers to belong to Japan? Does that fall within America’s treaty commitments to defend its ally?

There’s no guarantee that a U.S. president, especially Trump, would resort to war in either case. But these are among the scenarios war-gamers at the Rand Corporation have studied to see if the United States could prevent China from claiming territory by force. It’s not clear that the U.S. could.

Notably, the likeliest U.S.-China war scenarios take place in Asia—it’s not that a Chinese “victory” means the Chinese Communist Party takes over Washington, but that the U.S. can’t successfully eject China from Japanese-claimed territory or Taiwan. In an attempt to do so, besides cyberattacks, the United States could attack Chinese forces from the air or sea. The problem is that China has spent at least the past 20 years, partly informed by observations of how the U.S. conducted the Gulf War in the 1990s, preparing for exactly this kind of conflict, and investing in defenses that could violently thwart a U.S. approach.

It has missiles that can sink ships. It has missiles that can down airplanes. And it has missiles that could theoretically reach U.S. regional bases in Japan and Guam, leaving planes and runways vulnerable to attack. “Many Chinese observers suggest that missile strikes on air bases would be part of the opening salvos of a war,” notes Rand’s “U.S.-China Military Scorecard.” Shutting down such a base even for a matter of days, according to Rand, could be enough to change the course of the conflict.

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“The Chinese don’t have to comprehensively defeat the United States militarily in order to achieve their near-term objectives,” David Ochmanek, a senior international and defense researcher at Rand, told me. “If their objective is to overrun Taiwan, that in principle can be accomplished in a finite time period, measured in days to weeks.”

Ochmanek participated in the Rand war games that showed the U.S. losing. “It’s not just that they’ll be attacking air bases in the region. They’ll be attacking aircraft carriers at sea,” Ochmanek said. “They’ll be attacking our sensors in space. They’ll be attacking our communications links that largely run through space. They’ll be corrupting the databases in our command systems. They’re going to try to suppress us in every dimension that they can.” They will try, but it’s also worth noting that many of these capabilities are untested and that, in contrast to the United States, China doesn’t have a lot of experience actually using its weapons in combat.