President Barack Obama has ordered an investigation into a series of hacking and cyber-attacks, blamed on Russia, that shook the US election season.
The hacks targeted emails at the Democratic Party and a key aide to presidential nominee Hillary Clinton.
In October, US government officials pointed the finger at Russia, accusing it of meddling in the US vote.
According to a secret CIA assessment reported by the Washington Post, Russia intervened to help Donald Trump win.
Mr Trump, who will succeed Mr Obama in the White House next month, has consistently disputed such allegations.
This week he told Time Magazine: “I don’t believe it. I don’t believe they [Russians] interfered.”
He added that he thought the accusation against Russia was politically driven.
Russian officials have denied the hacking accusations.
Quoting an unnamed “senior US official”, the Washington Post said “intelligence agencies” had “identified individuals with connections to the Russian government who provided WikiLeaks with thousands of hacked emails from the Democratic National Committee and others, including Hillary Clinton’s campaign chairman”.
At one point during the campaign, Mr Trump encouraged Russia by name to “find” Mrs Clinton’s emails, although he said after an outcry that he was being sarcastic.
Democrats claimed the hacks were a deliberate attempt to undermine Mrs Clinton’s campaign.
“The president wanted this done under his watch because he takes it very seriously,” said White House spokesman Eric Schultz.
“We are committed to ensuring the integrity of our elections.”
He described the review as a “deep dive” into “malicious” cyber-activity.
It will look at the methods, targets and the US government’s response, he said, and it will be completed before Mr Obama leaves office and hands over to Mr Trump in January.
“Given President-elect Trump’s disturbing refusal to listen to our intelligence community and accept that the hacking was orchestrated by the Kremlin, there is an added urgency to the need for a thorough review before President Obama leaves office next month,” Democratic Congressman Adam Schiff said in a statement.
It is unclear if the contents of the review will be made public.
