As America and China grow more economically and financially intertwined, the two nations have also stepped up spying on each other. Today, most of that is done electronically, with computers rather than listening devices in chandeliers or human moles in tuxedos.
And at the moment, many experts believe China may have gained the upper hand.
Though it is difficult to ascertain the true extent of America's own capabilities and activities in this arena, a series of secret diplomatic cables as well as interviews with experts suggest that when it comes to cyber-espionage, China has leaped ahead of the United States.
According to U.S. investigators, China has stolen terabytes of sensitive data - from usernames and passwords for State Department computers to designs for multi-billion dollar weapons systems. And Chinese hackers show no signs of letting up. "The attacks coming out of China are not only continuing, they are accelerating," says Alan Paller, director of research at information-security training group SANS Institute in Washington, DC.
Secret U.S. State Department cables, obtained by WikiLeaks and made available to Reuters by a third party, trace systems breaches - colourfully code-named "Byzantine Hades" by U.S. investigators - to the Chinese military. An April 2009 cable even pinpoints the attacks to a specific unit of China's People's Liberation Army.
Privately, U.S. officials have long suspected that the Chinese government and in particular the military was behind the cyber-attacks. What was never disclosed publicly, until now, was evidence.
U.S. efforts to halt Byzantine Hades hacks are ongoing, according to four sources familiar with investigations. In the April 2009 cable, officials in the State Department's Cyber Threat Analysis Division noted that several Chinese-registered Web sites were "involved in Byzantine Hades intrusion activity in 2006."
The sites were registered in the city of Chengdu, the capital of Sichuan Province in central China, according to the cable. A person named Chen Xingpeng set up the sites using the "precise" postal code in Chengdu used by the People's Liberation Army Chengdu Province First Technical Reconnaissance Bureau (TRB), an electronic espionage unit of the Chinese military. "Much of the intrusion activity traced to Chengdu is similar in tactics, techniques and procedures to (Byzantine Hades) activity attributed to other" electronic spying units of the People's Liberation Army, the cable says.
Reconnaissance bureaus are part of the People's Liberation Army's Third Department, which oversees China's electronic eavesdropping, according to an October 2009 report by the U.S.-China Economic and Security Commission, a panel created by Congress to monitor potential national security issues related to U.S- China relations. Staffed with linguists and technicians, the Third Department monitors communications systems in China and abroad. At least six Technical Reconnaissance Bureaus, including the Chengdu unit, "are likely focused on defence or exploitation of foreign networks," the commission report states.
The precise relationship with the Chinese Army of suspected hacker Chen Xingpeng could not be immediately determined by Reuters. A spokesman for the Chinese embassy in Washington did not respond to multiple requests for comment. The U.S. State Department declined to comment.
But the leaked cables and other U.S. government reports underscore how Chinese and other state-sponsored and private hackers have overwhelmed U.S. government computer networks. In the last five years, cyber-intrusions reported to the U.S. Computer Emergency Response Team, a unit of the Department of Homeland Security, have increased more than 650 per cent, from 5,503 incidents in fiscal 2006 to 41,776 four years later, according to a March 16 report by the Government Accountability Office.
THE BUSINESS OF SPYING
The official figures don't account for intrusions into commercial computer networks, which are part of an expanding cyber-espionage campaign attributed to China, according to current and former U.S. national security officials and computer-security experts.
In the last two years, dozens of U.S. companies in the technology, oil and gas and financial sectors have disclosed that their computer systems have been infiltrated.
In January 2010, Internet search giant Google announced it was the target of a sophisticated cyber-attack using malicious code dubbed "Aurora," which compromised the Gmail accounts of human rights activists and succeeded in accessing Google source code repositories.
The company, and subsequent public reports, blamed the attack on the Chinese government.