An anonymous reader writes "Officials at the Chinese Defense Ministry say hackers from the U.S. have been attacking Chinese military websites. 'The sites were subject to about 144,000 hacking attacks each month last year, two thirds of which came from the U.S., according to China's defense ministry. The issue of cyber hacking has strained relations between the two countries.' This follows recent hacks from people in China on high-profile U.S. sites, as well as a report accusing the Chinese government of supporting a hacking group. '[Defense Ministry spokesman Geng Yansheng] called on U.S. officials to "explain and clarify" what he said were recent U.S. media reports that Washington would carry out "pre-emptive" cyber attacks and expand its online warfare capabilities. Such efforts are "not conducive to the joint efforts of the international community to enhance network security," he said.'"