MOSCOW, Aug. 7 -- The money moved fast. Stolen from Russian citizens through phone-based fraud schemes, it passed through unregistered cryptocurrency exchange offices before disappearing abroad - all of it, according to Russian authorities, coordinated from Ukraine. On Friday, the Federal Security Service said it had shut that system down, at least in part.

Russia's FSB announced the detention of more than 20 employees of unregistered cryptocurrency exchange offices operating out of the Moscow City business center, the gleaming riverside complex of towers that has become Russia's primary address for financial services firms. Working alongside the Russian Interior Ministry, the agency said it had simultaneously dismantled nine separate ch...