The flight of suspected Chinese surveillance balloons has shown that Japan and Taiwan need to share “critical” intelligence about potential common aerial threats, a senior defence policymaker for Japan’s ruling Liberal Democratic Party said.

“We don’t have those bilateral relations with Taiwan, so we don’t cooperate on that, but Japan’s government will have to consider what it does next,” Itsunori Onodera, a former defence minister and an influential lawmaker in the ruling party, said in an interview.

Japan’s islands are within 100 kilometres (62 miles) of Taiwan, so their aircraft and ships often operate in close proximity.

Although Japan does not have official diplomatic relations with Taiwan, it worries that China would imperil Japanese national security if Beijing gained control over the self-governing island.

One way that Japan could share information with Taiwan could be through its close ally the United States, added Onodera, who said he had visited Taiwan in January, where he was briefed about threats posed to the island by China.

Japan on Tuesday said that it suspected Chinese spy balloons had flown over Japan at least three times, most recently in 2021.

Japan’s defence forces did not intercept any of them, but Tokyo may relax its rules of engagement to allow Japanese fighter jets to shoot them down, as the United States did this month, Onodera said.

“If an object were to sink to an altitude used by commercial aircraft or crash, even if the risk is only small, it still represents a danger to people,” he said

Japan on Wednesday said it had warned China that violations of its airspace by surveillance balloons were unacceptable.

China says the balloon shot down on Feb. 4 was a civilian weather-monitoring aircraft. Beijing has accused Washington of sending its own balloons into Chinese airspace, and on Tuesday alleged those objects had flown above other countries as well.