Microsoft said the Chinese hackers have been active since mid-2021 and have targeted critical US infrastructure organisations.

Microsoft has warned that Chinese government-backed hackers are likely pursuing cyber capabilities that could be used to "disrupt critical communications" between the United States and the Asia Pacific region in the event of a future US-China crisis. 

In a new report released Wednesday, Microsoft said the Chinese hackers have been active since mid-2021 and have targeted critical infrastructure organisations in the US territory of Guam and in other parts of the US as part of a stealthy spying and information gathering campaign. Among the organisations targeted are the maritime, transportation, and government sectors.

The report underscores the key role that cyber operations might play in present and future US-China power competition and territorial disputes in the Pacific. China has in recent years claimed a growing list of territories in the Pacific, in what US officials view as alarming expansionism from Beijing. 

In a separate advisory released Wednesday, the FBI, National Security Agency, and other US and Western security agencies said they believe the Chinese hackers could apply the same stealthy techniques against critical sectors "worldwide".

Responding to the tech firm's report, Liu Pengyu, spokesperson for the Chinese Embassy in Washington, said in an email late Wednesday: "The allegation by the US side that the Chinese government is 'supporting hacking' is completely distorting the truth."

US officials regularly cite China as the most persistent and prolific government hacking threat facing Washington.

Jen Easterly, director of the US Cybersecurity and Infrastructure Security Agency, said in February that Chinese hackers are too frequently going "unidentified and undeterred" in their infiltrations of US organisations.

US officials are also concerned that Chinese hackers have created footholds in Taiwan's critical infrastructure that Beijing may use to disrupt key services like electricity in the event of a Chinese invasion of Taiwan, a senior US defence official told reporters in March.

The official, who spoke on the condition of anonymity, compared the Chinese probing of Taiwanese infrastructure to how Russia previously used its hackers to infiltrate Ukraine's electric sector. Russian military hackers cut power twice in Ukraine in landmark attacks in 2015 and 2016, according to the US Justice Department and private experts. 

"Over the last decade, Russia has targeted a variety of critical infrastructure sectors in operations that we do not believe were designed for immediate effect," said John Hultquist, chief analyst at Google-owned security company Mandiant. "China has done the same in the past, targeting the oil and gas sector.

"Chinese cyberthreat actors are unique among their peers in that they have not regularly resorted to destructive and disruptive cyberattacks," Hultquist added, noting that the Microsoft report "is a rare opportunity to investigate and prepare for this threat".