Several Maritime Self-Defense Force vessels reportedly allowed unvetted personnel to handle top secret information related to national security, with the MSDF’s top uniformed officer signaling his intention to resign over the latest breach.

Ryo Sakai, the MSDF's chief of staff since 2022, is expected to quit his post and the Defense Ministry is considering disciplinary actions for several other high-ranking officers, local media quoted ministry officials as saying Saturday.

The revelations emerged after the ministry announced in April that five senior MSDF and Ground Self-Defense Force members — including the then-captain of the destroyer Inazuma — had been punished over the distribution of secret information to unvetted personnel within their units.

Although April’s case involved only internal leaks, with none to outsiders confirmed, Defense Minister Minoru Kihara ordered a ministry-wide investigation into the possibility of other incidents.

“These kinds of incidents must not happen in the Defense Ministry, which holds secret information necessary for the defense of Japan,” he said at the time.

But that investigation later confirmed that there were several other cases of senior officers allowing unqualified personnel to handle what Japan terms "specially designated secrets" aboard a number of other naval vessels, the ministry officials said.

This practice of assigning unqualified personnel to the ship's combat command center and allowing them to work under conditions where they could view secret information on monitors is believed to have occurred for quite some time, and likely meant the sailors were exposed to sensitive information on a regular basis.

Specially designated secrets, which are designated by the defense minister and others, include information related to defense, diplomacy and other matters that could do severe damage to national security if possessed by an adversary. In order to handle such information, applicants must pass an assessment that covers their background, criminal record and mental health, as well as other aspects.

The Defense Ministry is expected to announce the results of the latest probe and any disciplinary actions by the end of the month, with NHK quoting a senior defense official as saying that the Prime Minister's Office had also been made aware of the incidents.

News of Saturday’s leaks followed revelations in 2022 that an MSDF captain had leaked secrets to a former MSDF admiral. That case, in which the captain was later fired from his post and referred to prosecutors, was the first punishment under a landmark state secrets law that Japan passed in 2013. Prosecutors decided in 2023 not to indict him due to insufficient evidence.

Japan has in recent years worked to plug holes in its national security framework as it looks to become more active in bilateral and multilateral defense projects that had once been off-limits to the pacifist country.

Building on the state secrets law, parliament in 2022 passed an economic security bill aimed at protecting technology and reinforcing crucial supply chains, while imposing stricter oversight of domestic firms working in sensitive sectors and on critical infrastructure.

This May, parliament also passed a bill that crafts a new “security clearance” system, granting certain individuals special access to classified economic information — part of a bid to stem leaks of critical data and create more business opportunities.

[bio]Information from Jiji added[bio]