A helicopter, presumed to be Russian, violated Japanese territorial airspace over their northernmost island of Hokkaido, Japan's Ministry of Defense said on Oct. 31.
The ministry said that fighter jets from Japan's Air Self-Defense Force were scrambled to respond.
The Japanese media outlet Kyodo News added that the ministry had "lodged a stern protest with Moscow over the incident through diplomatic channels."
Japan has complicated relations with Russia due to a complex history of competition and their close proximity. Hokkaido is located only 40 kilometers away from the Russian island of Sakhalin at their closest point.
There is also a territorial dispute concerning a string of islands called Japan's Northern Territories, known in Russia as the Kuril Islands, which have been occupied since 1945.
Russia withdrew from negotiations about the status of the islands after Japan imposed sanctions following the beginning of the full-scale invasion.
Japan has also provided Ukraine with a variety of aid, including military equipment, medical assistance, and the creation of a working group to help restore Ukrainian agriculture.
In total, Japan has sent Ukraine more than $7.5 billion in aid, the Ukrainian Ministry of Finance said in August 2023.