Ukraine live briefing: Separatist leaders gather in Moscow ahead of Russian annexation ceremony

Images released Thursday by the Swedish Coast Guard show a large mass of methane bubbles on the sea surface emanating from the leaks.

Cautioning that it was a preliminary estimate, Bjorn Lund, director of the Swedish National Seismic Network told The Washington Post’s Ellen Francis and Meg Kelly that the strength of the larger second blast was equivalent to 100-200 kilograms (220-440 pounds) of TNT. With the consensus among European leaders that sabotage was involved, suspicion is increasingly falling on Russia, which has denied all responsibility.

Amar Nadhir, Mary Ilyushina and Isabelle Khurshudyan contributed to this report.