An anonymous senior intelligence official told NBC news that the US would only deploy its own cyber attack “if necessary”.
It has been an open secret for years that the US has infiltrated critical online infrastructure of other nations like Russia and China, while the US has accused them of doing the same.
Days before the 2016 presidential election, US officials are concerned that adversaries could cause mayhem on Tuesday by releasing fake documents, creating bogus social media profiles to spread misinformation online such as rigged counting and tampering with state voting registration systems.
The news comes the same day that the hacker “Guccifer 2.0” - a front for Russian intelligence - tweeted that it would monitor the US elections “from inside the system”.
The Department of Homeland Security briefed reporters on Friday that they were “very concerned” about confusion on election day, but were confident that no breach would influence the result of the election.
Representative Adam Schiff of the House Select Committee on Intelligence told CNN: “They are capable of doing damage, they are capable of sowing further disarray.
“Will they end up doing it? We don't know, and I think we are taking all the precautions that we can.”