I think as a foreigner it is a little easy to miss how significant this is. The timeline of the war bleeds together and people who don't live in Ukraine can easily forget that Crimea was taken a long time ago... all the way back in 2014.

Ukrainian military commanders being able to say this confidently isn't just a sign that the meager territorial gains russia has obtained since the start of the 3 Day Special Military Operation might all vanish in what seems like a snap of a finger compared to the lives and time it took for russia to gain them.... it is a sign that Ukraine is uprooting the entire apparatus of russian power in the region that has had more than a decade to gain a foothold.

It is important to understand that for the average russian Crimea is far more relevant than basically any other territory taken from Ukraine from what I understand, it is a tourist destination spot that is also useful for its coastline and maritime access it provides, the fact that Ukraine can credibly say it will in the near future cut off Crimea is one of immense historical significance. It means this is the beginning of the end for russia, an end that might not actually be that long if russia doesn't come to the table with a realistic peace offer soon. Once air defenses systematically collapse there is no way to sustain a war machine capable of a large general offensive....

In the realm of "hearts and minds" russia losing Crimea after it had posessed it for over a decade from a conflict russia chose to begin is a major blow to the war effort and its general cultural support even if people are unable to discuss it too publicly.