Hacking operations linked to the Chinese government are aimed, in part, at gathering information about US drone technology, security analysts say. American cybersecurity firms say they tracked the hackers to a building occupied by the People\'s Liberation Army, indicating China\'s desire to be at the forefront of drone manufacturing, The New York Times reported Friday. Chinese hackers attacked at least 20 foreign defense contractors during a two-year period, targeting their drone technology, said Darien Kindlund, manager of threat intelligence at California-based FireEye, which monitored the attacks. \"It seems to align pretty well with the focus of the Chinese government to build up their own drone technology capabilities,\" he said. The Chinese military has not said how many drones it has, but a report by the Taiwan Defense Ministry estimated the number at more than 280 for the Chinese air force alone in 2011. That would mean only the United States, with its 7,000, has a larger drone fleet. A Pentagon advisory committee said in 2012 China\'s focus on drone systems was \"alarming.\" The Chinese navy deployed a drone this month near the Diaoyu Islands, a chain of islands also claimed by Japan, in China\'s first such use of the aircraft, said Ian M. Easton, a military analyst with the Project 2049 Institute in Virginia. Esaton said China is at the vanguard of using drones in contested maritime waters. While U.S. drones have been used to hunt down and kill terrorists, they are not designed \"to enter into contested or denied air space,\" he said. Copyright 2013 United Press International, Inc. (UPI). Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI\'s prior written consent.