Chinese state-backed hackers have infiltrated US communication systems in the Pacific, Microsoft has said, prompting fears that Beijing could cut off American military channels during an invasion of Taiwan.

Security researchers at Microsoft said hackers codenamed “Volt Typhoon” were caught infiltrating critical national infrastructure on the Pacific island of Guam, which acts as a crucial military staging post for the US in the region.

Microsoft said the “stealthy and targeted” campaign had been ongoing since at least 2021 and “has targeted critical infrastructure organisations in Guam and elsewhere in the United States.” 

“In this campaign, the affected organisations span the communications, manufacturing, utility, transportation, construction, maritime, government, information technology, and education sectors,”  researchers said.

Hackers appear to be using their access to spy on US operations but Microsoft warned that the group was “pursuing development of capabilities that could disrupt critical communications infrastructure between the US and Asia region during future crises.”

A major telecoms cable linking Japan and Australia runs through Guam, while another connects Taiwan and Singapore to Tokyo.

Guam is also a major staging post for the US military in the western Pacific. It would play a significant part in reinforcing Taiwan in the event of a Chinese invasion.