The video was posted on a Chinese video-sharing website in March. It appears to show the destroyer Izumo docked at an MSDF base in Yokosuka City, south of Tokyo.
Video posted on a Chinese video-sharing website.
The ministry said on Thursday that the video was likely authentic. It said its analysts had examined the shape of the vessel and the number on its deck, as well as the surrounding area, including vegetation.
Japanese Defense Minister Kihara Minoru told reporters on Friday that he accepts the analysis gravely, because if a drone can inflict damage on a defense related facility, Japan's defense could be seriously undermined.
Kihara said the ministry will intensify security around facilities related to the ministry.
MSDF's largest escort vessel
The Izumo is the largest escort vessel of the Maritime Self-Defense Force and is scheduled to be adapted to allow fighter aircraft to take off and land.
"Not AI" says uploader
The video was uploaded on the Chinese video sharing website "bilibili" in late March. It was later reposted on X, drawing attention in Japan as well. Some commenters speculated that it might have been faked using generative AI.
But someone posting on social media site X, claiming to be the person who uploaded the video on bilibili, insisted that the video is authentic.
Along with the words "For anyone who thinks it's fake," the person released images of what appears to be the flight route of the drone as well as images that seem to show the Izumo from various angles.
In addition, on Wednesday, when NHK reported that the footage of Izumo was "possibly real," the person posted a message saying "It took a month for the Japanese army to just realize," and released several similar images and videos.
The account does not give any motivation for shooting and releasing the video. It uses simplified Chinese characters that are used in mainland China. It also includes posts in other languages, including English, French, and Japanese. The account also has statements saying the poster is outside the country, safe and has not been arrested. One post refers to "a future war."
Video of US aircraft carrier
A video of another vessel was posted to the same account on Wednesday, showing a bird's-eye view of a large ship with a bridge bearing the number 76. That is the identification number of the US Navy's nuclear-powered aircraft carrier USS Ronald Reagan.
The video suggests maintenance work is underway, as people are seen moving about on the deck. There also appear to be green nets covering parts of the deck and bridge.
Yokosuka City officials say the USS Ronald Reagan was at the US Navy's Fleet Activities Yokosuka, adjacent to the MSDF Yokosuka base, from last November to May 5 for supplies and maintenance.
Drone flight restrictions in Japan
A Japanese law bans drones from flying over important facilities and their surrounding areas without permission from authorities.
The facilities subject to the flight ban include the Imperial Palace, the Prime Minister's office, the Diet building, foreign diplomatic missions, airports, nuclear power plants, and defense-related facilities.
The law designates the area above such facilities as red zones, and the surrounding areas with a radius of about 300 meters as yellow zones.
If a drone enters a yellow zone and the pilot ignores a police instruction to stop the flight, they can be sentenced to up to one year in prison or fined up to 500,000 yen.
If a drone enters a red zone, the same punishment can be applied even without such an instruction.
The defense ministry says generally speaking, it uses radar and optical sensors to detect drones, as well as looking for radio waves exchanged between pilots and drones.
It also says there are ways to deal with such drones, including sending out radio waves that obstruct flights and force them to land, or shooting nets to capture them.
Lawmakers express concern
Lawmakers of the ruling Liberal Democratic Party discussed the issue at a meeting on Thursday. Former Defense Minister Onodera Itsunori says "The Defense Ministry and others should have been closely monitoring the area, but despite that, such a video was taken. It's a critical issue that ministry officials and other relevant authorities should study thoroughly to make appropriate preparations."
Expert: A shocking event
Takushoku University's Professor Sato Heigo is an expert in defense policy. He says it is shocking that a drone could intrude into a vital SDF facility near a US military base and film the destroyer.
"How to obstruct drones that aim to gather information is becoming a major issue for other countries too. It is not very efficient to allocate human resources to detecting drones, so it would be reasonable to deal with them in a mechanical manner," he says. "Security responses to incidents always change as technology progresses. The Self-Defense Forces need to continue to monitor changes in technological movements in detail and consider how to deal with them effectively and efficiently."