Russian sources state that the bridge was blown by “surface” or underwater drones, and it was carried out by the joint efforts by SBU (Security Service of Ukraine) and the Navy of Ukraine
Based on the newly surfaced footage of the Crimean bridge, it appears highly likely that an autonomous uninhabited underwater vehicle was indeed deployed by the special units of the Main Intelligence Directorate of Ukraine.
There are reports suggesting that this underwater drone, which can also navigate on the surface, is equipped with a warhead weighing approximately 500 kg.