The use of suspected Chinese surveillance balloons has shown that Japan and Taiwan need to share "critical" intelligence about potential common aerial threats, a senior defense policymaker in the ruling Liberal Democratic Party has 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," said Itsunori Onodera, a former defense minister and an influential lawmaker in the ruling party, in an interview.

Some of Japan's islands are within 100 kilometers 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.

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

Japan did not intercept any of them, but on Thursday defense ministry officials briefed Onodera and other LDP lawmakers about a planned change in military engagement rules to allow Japan's air force to shoot down unmanned aircraft, including balloons that could endanger other air traffic or people on the ground.

"The rules currently cover manned aircraft or military aircraft. The change will add unmanned aircraft to those," Minoru Kihara, one of the lawmakers, told reporters after the briefing. The Self Defense Force will begin training pilots to engage those targets, he added.

Japan said Wednesday that it had warned China the 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.