US warned Japan that China was hacking its defence networks, officials say
- Senior US national security officials were worried that sensitive information that the US shares with some allies could be at risk as a result of the breach
- Concerns over the cyberattack prompted visits from multiple US delegations, but Japan did not seem to be taking sufficient action to boost security
The US warned Japan over the course of a year that Chinese state hackers had infiltrated its defence networks before Tokyo took sufficient action to try to secure them, according to current and former US officials.
Senior US national security officials grew increasingly concerned that sensitive information that the US shares with some allies could be at risk as a result of the breach, which was discovered several years ago. That prompted multiple US delegations since 2020 to fly to Tokyo to warn Japan, according to the officials, who asked not to be identified discussing the sensitive matter.
Still, the US saw insufficient evidence Japan was taking action to secure its networks despite warning of a problem, said a former intelligence official. General Paul Nakasone, director of the National Security Agency and commander of US Cyber Command, was among US officials who visited Tokyo to flag the issue.
But Japan wanted proof of the infiltration, said the former official, who added that intelligence is sometimes too sensitive to share specifics. Japan also was reluctant to let the US into its networks, the former official said.
Only after Anne Neuberger, deputy national security adviser for cyber and emerging technology, visited Japan in mid-November 2021 did the US and Japan chart a successful way forward, according to the officials. Japan has since set about boosting its cybersecurity defences, although the US is eager to see it do still more, according to statements from both countries this year, in addition to national security experts.
