The United States faces a mounting danger from cyber attacks on its infrastructure while digital espionage threatens to undercut the military's technological edge, the intelligence chief said Tuesday.

Citing "increasing risk to US critical infrastructure," National Intelligence Director James Clapper said in an annual report to Congress that "unsophisticated" attacks could penetrate poorly protected computer networks for power grids or similar systems.

The threat of a large-scale digital assault that could cripple a regional power network was genuine but remained a "remote" possibility, the report said.

"We judge that there is a remote chance of a major cyber attack against US critical infrastructure systems during the next two years that would result in long-term, wide-scale disruption of services, such as a regional power outage," it said.

The report placed more importance on cyber threats than previous years, with more words on the problem than on Islamist militants in Afghanistan.

Countries with advanced cyber capabilities, such as Russia and China, were unlikely to launch a massive digital assault on the United States unless there was a military conflict or grave crisis that put their national interests at risk, according to the report.

But "there is a risk that unsophisticated attacks would have significant outcomes due to unexpected system configurations and mistakes, or that vulnerability at one node might spill over and contaminate other parts of a networked system," it said.

China says willing to work with US against hacking
Beijing (AFP) March 13, 2013 - China has expressed a willingness to cooperate with the United States and others to combat hacking, after a top US official warned the international community was losing patience with Beijing.

Foreign ministry spokeswoman Hua Chunying, while reiterating China's position that it is a victim of attacks in cyberspace, said Beijing was in favour of global cooperation on the issue.

"What is necessary in cyberspace is not war, but rather regulation and cooperation," she told a regular briefing Tuesday.

"China wants to develop constructive dialogue and cooperation and joint safeguarding of the peace, safety and cooperation of cyberspace together with the international community including the United States," she said.

China has repeatedly made such offers in the past.

Such cooperation needs to be "based on the principle of mutual respect and trust", said Hua, calling the issue a "global problem".

She spoke after National Security Advisor Tom Donilon said in New York on Monday that Beijing must take steps to investigate and stop cybercrime.

Last month a report from US security firm Mandiant said a unit of China's People's Liberation Army had stolen hundreds of terabytes of data from at least 141 organisations, mostly based in the United States.

"This is not solely a national security concern or a concern of the US government," Donilon said, adding that US businesses were increasingly worried about theft of their secrets "through cyber-intrusions emanating from China".

A US congressional report last year named China as "the most threatening actor in cyberspace".

Beijing has flatly rejected such accusations. Following the Mandiant report. China's defence ministry countered that US-based hackers carried out regular attacks last year on two Chinese military websites.

Ministry spokesman Geng Yansheng also said that the Chinese military has no cyber warfare units.

Guo Longlong, a researcher in American Studies at the Shanghai Institute for International Studies, believes the claims that China is not doing enough to combat hacking are unfair.

"We don't have advanced technologies to protect ourselves from cyber theft," he told Wednesday's Global Times newspaper. "So we are actually more vulnerable."