By Matthew Miller SINGAPORE (Reuters) – U.S. technology companies including Cisco Systems Inc and IBM Corp are facing unprecedented difficulties selling their goods and services in China, as fallout from the U.S. spying scandal starts to take a toll. Cisco said on Wednesday that its revenue would drop 10 percent this quarter, and continue to contract until the middle of 2014, in part due to a backlash in China against revelations about U.S. government surveillance programs worldwide. The U.S. government isnt doing any favors for Cisco, said Evercore Partners analyst Mark McKechnie, after the companys shares fell 10 percent in late trade. In June, former National Security Agency contractor Edward Snowden revealed the spy agency had hacked network backbones around the world to gain access to sensitive information.