What I was concerned about in particular was making sure [the DNC hack] wasn’t compounded by potential hacking that could hamper vote counting, affect the actual election process itself. So in early September, when I saw President Putin in China, I felt that the most effective way to ensure that that didn’t happen was to talk to him directly and tell him to cut it out and there were going to be serious consequences if he didn’t. And in fact we did not see further tampering of the election process.

Barack Obama

Per TOP-SECRET NSA REPORT DETAILS RUSSIAN HACKING EFFORT DAYS BEFORE 2016 ELECTION, The Intercept