After midnight on a Monday in late September, seismographs in Sweden suddenly picked up a violent disturbance that jolted the floor of the Baltic Sea south of the rocky island of Bornholm, a onetime Viking outpost that is a part of Denmark.
Hours later — at 7 p.m. local time — it happened again: a series of underwater explosions farther off the island’s northeastern coast.
The next morning, photographs showed enormous blooms of methane bubbling on the ocean surface above both explosion sites, confirming reports of a severe loss of pressure in Nord Stream 1 and 2, the natural gas lines linking Russia and Germany.