Thus most regional governments welcome the current American “pivot” or “rebalancing” toward Asia; they want a continued U.S. presence to counter China’s growing ability to project military power. But this confounds the Sino-American relationship. Beijing complains that Washington’s real goal is to deny China its proper global role and “contain” it, much as it sought to contain the Soviet Union in past decades. U.S. officials say otherwise—that a rising China cannot be kept down, but does need to participate in global governance more fully and assume greater responsibility for its functions. All this gives Presidents Xi and Obama much to discuss.

Meantime, North Korea and cybersecurity offer immediate tests. Both sides want a peaceful, non-nuclear Korean peninsula but in U.S. eyes China does too little to rein in its neighbor and sometimes ally. Xi recently did warn North Korea to stop making trouble, and China reportedly now enforces United Nations trade sanctions that it previously supported more in word than in deed. But it remains unclear how far China will go, or what the North Korean response would be. However, if Obama concludes that Xi isn’t ready to do all that is feasible, the Sunnylands meeting could prove more tense than desired.

Likewise for cybersecurity. All major nations do some electronic spying on others, a murky area where none are pure. But the United States believes China has turned stealing commercial as well as security secrets into state policy—with business data passed along to help Chinese companies beat down foreign competitors. China both denies the charge and says it is ready for negotiations; without some broad agreement on cyber rules, further progress on vital economic relations could suffer.

The Obama administration contends that America’s future prosperity relies on closer links to Asia, not least China. Beijing, meanwhile, realizes it needs continued access to the American market and a flow of foreign investment and expertise. But to succeed the two governments must overcome their security differences and reach clearer understandings about how to live together. The meeting at Sunnylands, once a rich man’s retreat for aging movie stars, could tell the world if it can be done.

Robert Keatley is a former editor of The Asian Wall Street Journal and the South China Morning Post, both of Hong Kong.