This is actually great news. No reason to have a nuclear strike on US or its naval/military assets globally as a response.
Kursk was by far the stupidest Ukrainian move in the war, and they are losing badly there now. If Ukraine hits the nuclear plant or gas terminal though (not a defensive move outside their area of combat), US better immidiately cut off aid/support or get nuked.
This has the potential to be mostly nothing, and get Ukraine to negotiate withdrawal from Kursk to keep some of its last Ukrainians.