Senior U.S. officials will answer questions at a Senate hearing expected to be dominated by the assessment from intelligence agencies that Russia meddled in the presidential election to help Donald Trump win.
The Senate Armed Services Committee's cyberthreats hearing Thursday comes a day before the president-elect receives a briefing by the CIA and FBI directors — along with the head of national intelligence — on the investigation into Russia's alleged hacking efforts.
Trump has criticized their findings and even seemed to back WikiLeaks founder Julian Assange's contention that Russia did not provide him with hacked Democratic emails.
In new tweets early Thursday, Trump backed away from his apparent embrace of Assange. Trump blamed the "dishonest media" for portraying him as agreeing with Assange, whose organization has been under criminal investigation for its role in classified information leaks.
"The media lies to make it look like I am against 'Intelligence' when in fact I am a big fan!" Trump wrote.
The committee's session is the first in a series aimed at investigating purported Russian cyberattacks against U.S. interests and developing defenses sturdy enough to blunt future intrusions.
"We will obviously be talking about the hacking, but the main thing is the whole issue of cybersecurity," the committee chairman, Sen. John McCain, R-Ariz., said before the hearing. "Right now we have no policy, no strategy to counter cyberattacks."
Scheduled to testify were James Clapper, the national intelligence director; Marcel Lettre, the undersecretary of defense for intelligence; and Adm. Michael Rogers, National Security Agency chief and the top officer at the U.S. Cyber Command.
Accusations Russia interfered in the 2016 election by hacking Democratic email accounts have roiled Washington for weeks. President Barack Obama struck back at Moscow in late December with penalties aimed at Russia's leading spy agencies, the GRU and FSB, that the U.S. said were involved. The GRU is Russia's military intelligence agency. The FSB is the main successor to the Soviet-era KGB.
But Trump easily could rescind the sanctions. So far, he has publicly refused to accept the conclusion that Russia is responsible for the attacks. Trump this week escalated his criticism of U.S. intelligence professionals, such as Clapper, by tweeting, without evidence, that an upcoming briefing on the suspected Russian hacking had been delayed until Friday, and said, "perhaps more time needed to build a case. Very strange!"
Intelligence officials said there had been no delay.
Trump suggested Wednesday in a tweet that one of Russia's primary targets, the Democratic National Committee, could be to blame for being "so careless."
The penalties imposed by Obama came after he pledged a "proportional" response to the hacking of the Democratic Party and presidential nominee Hillary Clinton's campaign chairman. Emails stolen during the campaign were released in the final weeks by WikiLeaks.
CIA Director John Brennan said in a Dec. 16 message to employees that the FBI agreed with the agency's conclusion that Russia's goal was to support Trump in the election. Brennan wrote that he also had spoken with Clapper and said "there is strong consensus among us on the scope, nature, and intent of Russian interference in our presidential election."
Moscow has denied the hacking allegations and dismissed Obama's sanctions as an attempt to "harm Russian-American ties." Although Russian President Vladimir Putin rebuked the Obama administration for trying to punish Russia, he said his country would not immediately retaliate and would instead wait for a new U.S. approach after Trump takes office.
Trump praised Putin's move and called him "very smart."
To buttress the case for sanctions imposed by Obama and to expose Russia's cybertactics, the Homeland Security Department released a report prepared with the FBI that for the first time officially tied cyberattacks into the DNC email accounts to hackers affiliated with the GRU and FSB.