Agreed that based on earlier events, Russia would not respond with nukes. But, attacking those ships would be a declaration of war regardless.

Perhaps a more realistic response would be them to destroy a selected US naval base with hypersonic missiles that have conventional but still powerful warheads, launched from either those said subs or ships on the surface.

It also should be noted that the ships Ukraine managed to destroy on the Black Sea were mostly older, smaller vessels without decent AD systems. And maybe not adequately prepared for drone attacks. That would not be the case with the ships that are in question now.

It’s an extremely dangerous game they are playing here, approaching a Cuban missile crisis 2.0, if you will.