In the very long podcast I mentioned earlier Theiner, @noclador on twitter, tackles the ATACMS vs. Hrim-2 issue. He rules in favour of the former because, as I understood it, of the two only ATACMS (being a non ballistic missile) has the attack profile that would allow it to 1. seemingly completely ignore air defences and 2. cause the pattern of damage seen on the bridge. He hypothesis that the US might have given Ua access to the ATACMS guidance system, to mount on a Hrim-2 (3?), but ultimately discards that idea as being too improbable.