Who are the Volcano Group, mystery saboteurs behind a five-day Berlin blackout? (theguardian.com)

• Five-day Berlin blackout caused by sabotage
• Volcano Group unknown, no claim of responsibility
• Attack shows sophisticated grid knowledge

"A previously unknown group called the Volcano Group is believed responsible for a five-day blackout in Berlin. The attack targeted critical power infrastructure, causing widespread disruption. No claim of responsibility has been issued, but the method suggests sophisticated knowledge of the grid. Authorities are investigating it as state-level sabotage, raising concerns about Europe's energy security."