Japanese leaders have protested after seeing a Russian military plane fly into their airspace. Prime Minister Kishida Fumio demanded on Monday that such an intrusion never happen again.

"We have lodged a very strong protest through diplomatic channels and urged the Russian government to prevent a recurrence," Kishida said. "We are determined to defend our land, sea and air and make sure to keep our eyes on the situation."

Defense ministry officials said a IL-38 patrol aircraft flew near Rebun Island in Hokkaido prefecture around one in the afternoon then returned twice over the next three hours. They said each violation lasted between 30 and 60 seconds.

Commanders responded by scrambling Air Self-Defense Force jets. They said the Russians did not respond to radio warnings. So, the Japanese crews fired off flares. They became the first to do that since the introduction of measures designed to respond to such intrusions.