Yeah, I forgot about the subs. Though Block V Tomahawks could theoretically reach Novorossiysk and I wouldn't put it past Russia having maintenance issues precluding use of their whole fleet.
Still though, doing substantial damage to the Russian surface fleet would cripple their ability to resupply units in Crimea and Southern Ukraine, which significantly enables a successful Ukrainian counterattack in these areas, and that very well could settle into a long war of attrition.
Coastal missiles or Russian air force could always be a threat to Ukrainian sea traffic as well, regardless of Russian subs or surface ships, so I think it is correct that really only a treaty can open up Ukraine to substantial commercial sea traffic.
Still though, doing substantial damage to the Russian surface fleet would cripple their ability to resupply units in Crimea and Southern Ukraine, which significantly enables a successful Ukrainian counterattack in these areas, and that very well could settle into a long war of attrition.
Coastal missiles or Russian air force could always be a threat to Ukrainian sea traffic as well, regardless of Russian subs or surface ships, so I think it is correct that really only a treaty can open up Ukraine to substantial commercial sea traffic.