While attention in Asia has been distracted by the North Korean nuclear crisis in the past year, China has continued to install high-frequency radar and other facilities that can be used for military purposes on its man-made islands in the South China Sea, a U.S. think tank said on Thursday. Chinese activity has involved work on facilities covering 72 acres (29 hectares) of the Spratly and Paracel islands, territory contested with several other Asian nations, according to the Asia Maritime Transparency Initiative of Washington's Center for Strategic and International Studies. The report cited satellite images.