That’s never going to happen. So while that may make a nice concise talking point, its just bluster.
Crimea is Russian territory. Historically. I was shocked when they allowed Ukraine to keep at the breakup of the Soviet Union, and I was entirely unsurprised when they took it back. Crimea is Russia. It historically was never Ukraine.
Now, helping Ukraine defend its eastern provinces, that’s a different issue. While they are linguistically Russian, they are historically Ukraine. But Crimea, forget it.
If you want to get historical about it, the Romans ruled Crimea from around 15 BC until the 3rd Century sometime. After falling, successively, to the Goths, Huns and Khazars over the next few hundred years, it became split between Kiev and the Byzantines. The Mongols occupied large chunks in the 13th Century. The Genoese and Venetians also occupied areas. The Tatars conquered most of the Crimea in the 1400s and ruled it as a tributary state to the Ottomans. In 1783, the Ottomans ceded it to Russia after the Russo-Turkish War.
I say it goes back to the Mongols. Or maybe the Genoese.