President Donald Trump walks out of the Oval Office before speaking about Robert Mueller's investigation into Russian interference in the 2016 presidential election in the Rose Garden at the White House May 22, 2019 in Washington, DC.

U.S. President Donald Trump on Thursday directed the U.S. intelligence community to "quickly and fully cooperate" with Attorney General William Barr's investigation into the origins of special counsel Robert Mueller's Russia probe, according to a White House statement.

That investigation is looking into the government's authorization of surveillance on Trump campaign aides during the 2016 election. Trump has said that the surveillance was unlawful and could lead to "long jail sentences."

Barr announced shortly after Mueller concluded his investigation earlier this year that the Department of Justice was examining that surveillance, saying "spying did occur." In May, it was reported that Barr had appointed a U.S. attorney to look into the matter.

The White House signaled that information uncovered by Barr's investigation will be made public, and granted Barr the authority to declassify materials related to it. The White House said it would "ensure that all Americans learn the truth about the events that occurred, and the actions that were taken, during the last Presidential election."