• Japan’s defence minister says it would have the legal right to destroy any balloon that enters its domestic airspace.
  • Tokyo is investigating if balloons like the Chinese one shot down over the US have been used to probe Japan’s defences.

Japan is investigating reported sightings of balloons over its territory in recent years, due to growing concerns that China is deploying the relatively unsophisticated technology to obtain intelligence about Japan’s defences.

Defence Minister Yasukazu Hamada said on Tuesday under existing laws, Japan would have the legal right to destroy any balloon that intrudes into its domestic airspace.

Tokyo has been closely watching Washington’s response to a Chinese surveillance balloon that was tracked for about a week as it crossed North America — coming very close to sensitive American military facilities — before it was shot down by a fighter off the east coast on Saturday.

Japan is concerned because some weather models indicated it crossed into its territory before traversing the Pacific Ocean, and that other balloons may have been used to probe Japan’s defences in the past or may be used for the same reason in the future.

Deputy Chief Cabinet Secretary Yoshihio Isozaki said in a press conference on Monday that Tokyo had opened a probe over past balloon sightings over Japan, with similar aircraft reported in a number of northern locations, including the city of Sendai in June 2020. There were similar sightings over Aomori Prefecture in September 2021.

Isozaki declined to comment on the reaction of the Self-Defence Forces to the sightings for security reasons, but indicated Japan would from now on respond more forcefully.

“Intrusions into Japan’s territorial airspace constitute a violation, even if it is a balloon,” the Yomiuri newspaper quoted Isozaki as saying. “If necessary, we will take measures, including scrambling [ASDF fighters].”

japan f-15

A Japan Air Self Defense Force F-15 in July 2009.


US Air Force/Angelique Perez



And while the military has the right under the Self-Defence Forces law to act against intruders, ASDF aircraft are meant to force unauthorised aircraft to land or leave Japanese airspace. Fighters are only specifically permitted to destroy an intruder if it poses a threat to life or property, such as an inbound missile.

The law, however, is hazy on balloons and is now likely to be addressed, said Ryo Hinata-Yamaguchi, a project assistant professor at the Research Centre for Advanced Science and Technology at the University of Tokyo.

“Militarily, Japan is capable of shooting down one of these balloons, but there have to be clear procedures to follow before that can happen and there still needs to be a debate over the rules of engagement for a balloon,” he told This Week in Asia.

Re-examining previous cases when balloons entered Japanese airspace will be helpful in determining the threat to national security, he said, and then in devising legal and military countermeasures.

There are few other options for Japan, as the US has found out, with the only other realistic approaches being to use jamming technology to halt transmissions to and from the object, or letting it continue its journey uninterrupted, Hinata-Yamaguchi said. In the future, it may be possible to use lasers or other technology to bring a balloon to earth, he suggested.

Yoichi Shimada, a professor of international relations at Fukui Prefectural University, said the destruction of the balloon over the US had been “the appropriate course of action” and said he hopes Japan would use the same tactic in a similar situation.

“It is clear that China was using the balloon to carry out military reconnaissance against the US and it was in their airspace, so the response was the correct one,” he said. “I hope now that they are able to recover the information that the balloon collected and show it to the rest of the world.

“Ideally, it would be best to stop these balloons actually crossing [into] the US or Japan, but when they are seen over land then they must be brought down safely.”

Japan uses balloons for weather observations, but the prevailing winds mean that they typically travel east, over the Pacific, rather than over mainland Asia.

Tokyo also operates satellites to monitor the activities of its regional rivals and to be prepared for military challenges, although it relies heavily on information provided by the US for early warning of threats.

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