The Facts and Mysteries About Russia’s Hack of the U.S.

The broad, sophisticated and damaging hacking campaign that U.S. officials are blaming on Russia has alarmed security firms and sent shock waves through the U.S. government and private sector. Much remains unclear, including how many government agencies and private companies were hacked and what information was stolen or reviewed by the attackers. The hackers’ motive also remains a mystery: Was it espionage or something even more destructive?