No he probably couldn't. He could nuke it, but sending a bunch of planes against a city which has air defense cover is a good way to lose your airforce. He sure can't get artillery near it - because he'd have done it if that armor convoy could move. Instead it's getting bombed by Ukranian war planes.

Resistance fighters lose against an occupier at something like a 10:1 ratio - against the resistance. They lose on average 10 members for every occupation kill. You can prove this to yourself - what did the US lose in Afgahnistan vs the Taliban? For how many years?

You should always try and win the conventional war if you can do win at a better rate then that - which the Ukraine is.