Japanese authorities issued a joint advisory Wednesday about Salt Typhoon, a Chinese government-backed hacker group, in a document prepared by the United States and signed by a total of 13 countries including the U.K. and Canada.

The hacker group is linked to several Chinese telecommunications companies that provide services to the Chinese People's Liberation Army and China's Ministry of State Security, according to the document, released in Japan by the National Police Agency and the National Cybersecurity Office.

Information stolen by the group is eventually used by intelligence agencies, said the document, which was released under a framework called "public attribution" aimed at deterring cyberattacks by naming countries behind attackers.

According to the NPA, the group has targeted government agencies and critical infrastructure companies in various countries since 2021, infiltrating their computer systems and collecting information over an extended period.

There have been reports of damage from the infiltration of a major U.S. telecommunications company and from eavesdropping on voice calls of high-ranking government officials. In Japan, several cases of damage have been confirmed at infrastructure companies and organizations.

The document outlines attack methods, damage assessment procedures and ways to deal with attacks.