Japan refuses to confirm if China hacked its defence networks

‘We have not confirmed that classified information held by the defence ministry has been leaked due to a cyberattack’

File: Soldiers of the British army and the Japanese Self Defence forces take part in a joint military drill in Oyama (AFP/Getty Images)

Japan on Tuesday refused to confirm if any security information was leaked through a cyberattack after a report claimed China hacked into the country's defence networks.

Chinese military hackers allegedly gained access to a sensitive and classified defence network in Japan in 2020, which provided Beijing access to Tokyo's military capabilities, plans and assessments of shortcomings, the Washington Post reported on Monday.

The hack was discovered by the US National Security Agency (NSA), prompting heads of the agency to fly to Tokyo to brief the Japanese defence minister, who asked the US officials to alert the prime minister themselves, the newspaper report said.

NSA chief General Paul Nakasone, and then-White House deputy national security adviser, Matthew Pottinger, were part of the delegation. “It was bad – shockingly bad,” a former US military official who was briefed on the event told the newspaper.

Japan's chief cabinet secretary Hirokazu Matsuno told reporters on Tuesday that Japan and US have always been in close communication on various levels.

"Due to the nature of the matter, I am unable to provide further details of the communication but we haven't confirmed the fact that security information has been leaked due to cyber attacks," he said.

Mr Matsuno also said that cyber security is the foundation for maintaining the Japan-US alliance and that Japan will continue to work to keep its network firm and secure.

Separately, defence minister Yasukazu Hamada said: “We have not confirmed that classified information held by the defence ministry has been leaked due to a cyberattack," the minister said.

Japan’s slow response to improve its cyber network could impede greater intelligence sharing between the Pentagon and Japan’s Defence Ministry, the newspaper said, citing officials.

Chinese state-sponsored breaches have become increasingly common, with the US being the latest country targeted by hackers.

Since May, hackers have secretly accessed email accounts at around 25 organisations, including US government agencies, Microsoft and US officials have said. China has not yet commented on the incident.