Maybe you haven’t noticed recently how there already western weapon systems actively striking targets within Russia. Those same systems can deliver nuclear payloads.
So what your are saying is a falsehood based on the current realities on the ground.
I suppose any of the thousands of regular aircraft that Ukraine has "could" deliver a nuclear payload. But that would be a pretty stupid way to launch a first strike, and doesn't change the MAD equation in any way.
So what your are saying is a falsehood based on the current realities on the ground.