The Pentagon says it is confident about sharing intelligence with Japan, despite a US news report saying Chinese military hackers gained access to Japan’s most sensitive defence networks.

Deputy Pentagon press secretary Sabrina Singh told reporters the Pentagon remained “confident in our relationship with Japan”.

“We continue to coordinate with one of our greatest partners in the region, we continue to conduct exercises and bilateral and trilateral meetings,” she said.

Earlier this week, the Washington Post cited unnamed current and former US and Japanese officials as saying that Chinese military hackers gained access to Japan’s classified defence networks in 2020, accessing information about the US ally’s military capabilities, plans and assessments of shortcomings.

Japan’s Chief Cabinet Secretary Hirokazu Matsuno told a regular press briefing Japan could not confirm whether any security information had been leaked.

The Post quoted one former US military official as saying the breach was “bad — shockingly bad” and that the head of the US National Security Agency flew to Tokyo to brief the Japanese defence minister, who asked the US officials to alert the prime minister.

The paper said Japan had taken steps to strengthen its networks, but cited unnamed officials as saying these were still deemed not sufficiently secure from spying by China, which could impede greater intelligence sharing between the Pentagon and Japan’s Defence Ministry.

Ms Singh declined to comment on the Post report, saying the Pentagon would let Tokyo speak for its intelligence and cyber capabilities, but she added: “We feel confident in our relationship and the intelligence sharing that we do with Japan and we’re confident that we will continue that.”

The US National Security Agency did not immediately respond to a request for comment on the Post report, which comes ahead of a trilateral summit between the United States, Japan and South Korea, at which the three allies are expected to announce plans to step up security cooperation in the face of increasing concerns about China.

Asked about the Post report, Japan’s chief cabinet secretary said Japan and the US had 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,” Mr Matsuno said.

Mr Matsuno said cybersecurity was the foundation for maintaining the Japan-US alliance, and Japan would continue to work to keep its network firm and secure.

There was no immediate comment from Beijing.

The US, Japan and South Korea have been working on a joint statement for the summit to bind them more closely together on security issues, a US official said last week.

The official said the allies were discussing installing a trilateral leader-level hotline and were expected to unveil other measures, including strengthening trilateral exercises and moves to boost cooperation on cybersecurity, missile defence and economic security.

Reuters/ABC