Barack Obama will confront Chinese president Xi Jinping next week over a spate of cyber-attacks on the US, including the latest allegation that Chinese hackers gained access to more than two dozen of America's most advanced weapons systems.
The alleged cyber-attacks are the most serious of a series of issues creating friction between the US and China ahead of next week's summit in California. Military analysts described the scale of the alleged attacks as breathtaking.
The Chinese government denies any involvement in the attacks.
But a classified report by the Defence Science Board, a group of civilian and government specialists who advise the Pentagon on military developments, says advanced weapons systems compromised by hackers include missiles, fighter jets, helicopters and naval ships. A leaked copy was published by the Washington Post on Tuesday.