The pair met in 2012 when Xi Jinping was China's vice president
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Presidents Xi and Obama to talk cyber security

China's President Xi Jinping is in the United States for talks with US President Barack Obama.

It will be President Xi's first official visit to the US, and the high level meeting will take place in California.

Trade talks are on the agenda, but the more pressing issue that both sides want to tackle, are the recent allegations of cyber attacks, which came first from the US and then were countered by China.

The BBC's John Sudworth in Shanghai looks at a trade and political relationship that is both long and complicated.