I have to wonder how the calculus might change if Turkey decided to temporarily re-flag (or dual-flag, if that's a thing) freighters traveling between Bosphorus and Odessa. Firing one of them might change the 'peacetime' status of the Montreux Convention Regarding the Regime of the Straits - and the Rus would lose shipping access - which they need in order to supply their troops supporting the Assad regime in Syria.