If US ATACMS destroys Kerch, that may "provoke" Putin more somehow, as if spending a decade building up to invade, then invading Ukraine was not provocative enough. Russia air defenses and operations around Crimea need to get worn down first. Kerch is operating at significantly reduced capacity, that is good enough for now.
As for destroying the bridge the first time Russia says it was truck bomb, which doesn't make sense since all trucks going over the bridge are searched and x-rayed. One alternative explanation was Ukraine used some kind of seaborne drone to attack the bridge. Except their known sea drones look too small, even if a dozen were used. Despite official explanations or non-explanations, How Kerch really was attacked is still a unanswered question.
Ukraine's sea drones, Neptune anti-ship missiles, and the remaining Bayraktars are why Russia's navy has been locked up in Servastapol. Operator Starsky reported a sizable Russian naval force put to sea yesterday. We will know in a day or two what the current naval situation is.
KERCH BRIDGE Railway—
See the photo above of the burning tank cars that are burning and separated. That Russian train was stalled and not moving. Why was that? Bribery. My take is that separate explosives were pre-placed under the oil tank cars. These explosives went off at the same time as what explosives or missiles destroyed the Kerch roadway bridge for automobiles.
Extreme Ukrainian sabotage along with a British/American intelligence brain trust that stole the Kerch Bridge architectural plans and analyzed them. Or actually the Kerch Bridge architecture is standard Russian but needed to be analyzed for weak spots by the Brits and Americans. The railway bridge was warped and destroyed by the oil tank car fires and the massive under carriage explosives that set them on fire.