Summary:
- The U.S. government seized $400 million from Helix, a dark web cryptocurrency mixer service, in one of the largest cryptocurrency seizures ever.
- Helix was used to launder money and hide the origin of funds, often associated with illegal activities on the dark web.
- The seizure is part of the government's efforts to crack down on the use of cryptocurrency for criminal activities and to disrupt the financial infrastructure of these illegal operations.