Japan and Russia had a tense moment in the skies when a Russian military airplane entered Japanese airspace without permission. Japan's Defense Ministry called it a serious violation and quickly responded.

On Monday, a Russian Il-38 reconnaissance plane flew over Rebun Island, which is located in the far north of Japan, close to the main island of Hokkaido. This is a sensitive area, as both Japan and Russia have a history of disputes over territorial boundaries. Japan's Defense Minister,...