He said, Xi said

The Valentine's Day summit between Xi Jinping and Barack Obama could make for uncomfortable viewing. China's likely next president is due to meet the US leader in Washington - as his predecessor did ten years ago. Only this time the stakes are higher. Obama, facing a November election, is under pressure to talk tough. Xi is under pressure to stay cool, while appeasing hardliners back home.

When Hu Jintao visited George W Bush a decade ago, Sino-US relations were strained. Taiwan, and the crashing of a US surveillance plane in Chinese airspace, loomed large. But the war on terror created a common purpose. Aside from Congresswoman Nancy Pelosi's attempt to hand Hu a wad of letters about Tibet, the visit was unremarkable.

Three things are different now. Trade, supposed to be another common purpose, has created new tensions. China has failed to open key markets, and still restricts exports of strategic commodities. Obama, desperate to create jobs, has threatened tough action against nations like China which suppress their currencies to promote trade. It's also a popular theme with his potential Republican opponents, even though US firms and consumers are big beneficiaries of China's cheap labour.

Second, military tensions are back. America is returning troops to the Pacific, where China has low-level territorial disputes with just about everyone. And Beijing is more openly critical of US interventionism. It refuses to condemn Syria's human rights abuses, and vacillates over American sanctions on Iran. These topics vex the masses on both sides.

Then there's Xi, who seems more three-dimensional than the taciturn Hu. He loves Hollywood; his wife is a glamorous military folk singer, and his father a famed revolutionary. Xi has already broken the mould by criticising judgmental "foreigners with full bellies" on a Mexican visit in 2009. Some personality may be beneficial: Hu's indecipherability has only widened the Sino-US trust deficit. Both sides have good reasons to keep things friendly for now. Xi is not yet China's leader. Overplay his hand in Washington and he might never be. Obama wants to win the election, though won't want to start a second term with a new and powerful enemy. Once both men have secured their posts, then the sparks can fly.