Senior U.S. national security officials tell NBC News they are confident that Russian intelligence agencies hacked the Democratic National Committee.
The open question, they say, is whether those same intelligence agencies directly leaked material to WikiLeaks, in what would seem to be an unprecedented effort to influence the U.S. election.
The Russian government had the "motive, means and opportunity," one official said, and many officials believe it is likely the Russians gave the emails to WikiLeaks, but there is not yet definitive evidence.
A total of nearly 20,000 emails were stolen, among other data, officials say. The FBI and the NSA are now investigating who leaked the documents.