According to Monkey Werx it was a US Navy P-8 Poseidon that flew over the Nordstream pipeline the morning of the demolition. The USN P-8 dropped something that triggered or caused the pipeline explosion, not Norway. According to Wikipedia Norway has no P-8 Poseidons, only a few old P-3 Orions. The P-8 is a jet, the P-3 is a turboprop. Using Skyglass Monkey Werx tracked it as a US Navy P-8 Poseidon coming in from the Atlantic after refueling in Iceland. It refueled again over Europe and then continued its mission to the pipeline. After dropping its load that destroyed the pipeline it boogied on down the road at full throttle.
(The Skyglass coverage of this video starts around the 25:00 mark.)
Why did Seymour Hersh pin the P-8 on Norway? They don't have any.
Edit: Uncle Sam gave Norway some P-8 Poseidons at such a bargain. But who dropped the buoy on target? Why would the P-8 come from the Atlantic via Iceland? That's a long flight.