BEIJING—Chinese police issued wanted notices for three people they said engaged in cyberattacks against China on behalf of the U.S. National Security Agency, a rare step by Beijing as hostilities between the superpowers escalate.

A joint report [PDF] from China's computer emergency response centers (CERTs) earlier this month stated that more than 270,000 attacks on the Asian Winter Games were detected, 170,000 of which were allegedly launched by the US. The others were allegedly carried out by Singapore, the Netherlands, Germany, and South Korea.

Chinese security officials claimed on Tuesday that three individuals from the US National Security Agency (NSA) attacked the information infrastructure during the 9th Asian Winter Games held in the Northeastern city of Harbin in February.