Ukraine

They barely have the manpower to push forward even in Ukraine. Then again if they ever want to do it now is the time because in a few decades they're not going to have enough fighting age men. I just really doubt this. If the current war has taught us anything it's that they would get absolutely obliterated by Nato and there are no winners in a nuclear exchange. Also them using nukes in Ukraine/Europe would mean nuking themselves too because that's the direction wind is going to push the fallout. Though that assumes they would care about their civilian population which they clearly don't.