By Alina Selyukh and Doina Chiacu WASHINGTON (Reuters) – Fledging cooperation between the United States and China on fighting cyber crime has ground to a halt since the recent U.S. indictment of Chinese military officials on hacking charges, a senior U.S. security official said on Thursday. In May, the Justice Department charged five Chinese military members with hacking the systems of U.S. companies to steal trade secrets, prompting Beijing to suspend a Sino-U.S. working group on cyber issues. China denies the charges and has in turn accused Washington of massive cyber spying. Everything is really cold. Asked whether attempts to hack into U.S. networks that originate in China had slowed, the official said: They have been very active and this hasnt changed a bit. The new chill underscores the fragility of the efforts to ease tensions and mutual accusations of hacking and Internet theft between China and the United States, at the expense of the security areas where the nations had reached some understanding.