Answer:

 This means that such soldiers are siding with Satan since the war against Ukraine is a form of military aggression. True Muslims never initiate military aggressions; fighting within Islam is exclusively within cases of self-defense. That such Chechen soldiers have sided with the tyrannical, unjust Russian President, Vladimir Putin, is against True Islam (i.e., the Holy Quran only). Those siding with the unjust ones are also deemed as unjust ones; Islam denounces & is innocent of all unjust aggressors in all eras and regions.