Possibly a big mistake.
Conquer a big chunk of the Ukraine and they insurgency on their hands.
Most of Eastern Ukraine is pro-Moscow. Those Ukrs are not even real Ukrainian...they are Russian...flloded the zone with them decades ago.
Do better research. About 2-8% are ‘patriots’ and they are mostly contained to Western part, not counting carpetbaggers in Kiev. The rest would gladly part with the Kiev regime.