Ukraine is at war with Russia. Japan has a claim over the islands, which are currently held by Russia. For Ukraine, formally recognising Japan's claim to the i

Ukraine is at war with Russia. Japan has a claim over the islands, which are currently held by Russia. For Ukraine, formally recognising Japan's claim to the islands might achieve a few things. First, it might cause Japanese public opinion to change in favour of Ukraine, potentially increasing material Japanese support for the Ukrainian cause. Second, it might cause Russia to divert military resources to the east, in order to forestall any attempt by Japan to re-take the islands by force (though this is very unlikely). Third, it might be a bargaining chip in any future peace treaty between Ukraine and Russia. Most likely, both sides will have to agree to respect the territorial integrity of the other party, so Ukraine might withdraw its recognition of the Japanese claim as part of a deal with Russia. It's unliklely to be a significant factor, but every little helps in a negotiation. I'm sure these are other reasons, but these are the ones that occur to me.