Donald Trump
© Jonathan Ernst / Reuters
Former National Intelligence Director James Clapper and former acting Attorney General Sally Yates testify before the Senate Judiciary Committee's Subcommittee on Crime and Terrorism about alleged Russian meddling in the 2016 US presidential election.

Clapper incorrectly claimed that no Republican data was released during the campaign, WikiLeaks co-founder Julian Assange said on Twitter, offering documents published in August 2016 as proof.

The highly anticipated hearing is expected to fill in key details in the chain of events that led to the ouster of Michael Flynn, President Donald Trump's first national security adviser, during the administration's first month in office.


White House spokesman Sean Spicer confirmed media reports that former president Barack Obama had spoken against Flynn in a transition meeting with Trump.

"This is a guy who was very outspoken in his criticism of President Obama's policies," Spicer said of Flynn during the White House press briefing on Monday, going on to question why the Obama administration allowed Flynn to travel to Russia and did not revoke his security clearance.

"If they were concerned, why didn't they take any steps?" asked Spicer.

Yates was the acting attorney general at the time of Trump's first travel ban, and was fired after refusing to enforce it. On Monday, Trump urged the committee to question her under oath about classified information she was privy to ended up in the media, implying that the former Obama appointee may have been behind the leaks.