The sabotage in September of the Nord Stream pipelines carrying Russian gas to Europe has become one of the central mysteries of the war in Ukraine, prompting months of finger-pointing and guesswork.Now, new intelligence reporting has provided the first significant known lead about who was responsible.Guest: Julian E. Barnes, a national security correspondent for The New York Times.Background reading: Officials say there are still enormous gaps in what American spy agencies and their European partners know about the detonations.The Baltic seabed provided a nearly ideal crime scene.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.