President Barack Obama used an unusually lengthy and informal desert summit to present Chinese President Xi Jingping with detailed evidence of intellectual property theft emanating from his country, as a top US official declared that cybersecurity is now at the "center of the relationship" between the world's largest economies.
There were few clear policy breakthroughs on cybersecurity or other matters during Obama and Xi's two days of talks at the sprawling Sunnylands estate.
But officials from both countries said they were optimistic that the stronger personal ties forged between the two leaders could lay the groundwork for progress on issues including North Korea's provocative nuclear threats, climate change and economic issues.
Still, Obama's national security adviser Tom Donilon said resolving cybersecurity issues would be "key to the future" of the relationship.
Obama told Xi that "if it's not addressed, if it continues to be this direct theft of United States property, that this was going to be very difficult problem in the economic relationship and was going to be an inhibitor to the relationship really reaching its full potential," Donilon told reporters following the summit.
In their own recap of the meetings, Chinese officials said Xi opposed all forms of cyberspying and claimed no responsibility for attacks against the US.
Xi also emphasised during the summit that his country too had been a victim of cyberattacks.
