The move significantly escalates the administration's efforts to place those who investigated the campaign under scrutiny. It comes as House Speaker NancyPelosi discussed the potential need for an "intervention" with Trump.
In a directive,Trump ordered the CIA and the country's 15 other intelligence agencies to co-operate with the review and granted Barr the authority to unilaterally declassify their documents.
The move gave Barr immense leverage over the intelligence community and enormous power over what the public learns about the roots of the Russia investigation.
The order is a change for Trump,who last year dropped a plan to release documents related to the Russia investigation amid concerns from Justice Department officials who said making them public could damage national security.
At the time,Trump was being encouraged by a group of Republican Congress members to declassify the information.
One official,who spoke on the condition of anonymity to discuss classified matters,said previously that Barr wanted to know more about what foreign assets the CIA had in Russia in 2016 and what those informants were telling the agency about how President Vladimir Putin of Russia sought to meddle in the 2016 election.
Barr,who has used the word"spying"to describe how the Trump campaign was investigated,has been deeply involved in the department's review of how the intelligence was collected on it.