Politicians heading the Senate intelligence committee have focused squarely on Russia as they opened a hearing on attempts at undermining the 2016 US presidential election.
"Russian President Vladimir Putin ordered a deliberate campaign carefully constructed to undermine our election," Democratic Senator Mark Warner said.
Earlier on Thursday, Mr Putin again dismissed what he called "endless and groundless" accusations of Russian meddling in the US election, describing them as part of the US domestic political struggle.
He also said he is ready to meet with US President Donald Trump at an upcoming Arctic summit.
The hearing is to address how the Kremlin allegedly uses technology to spread disinformation in the US and Europe.
Mr Warner and the panel's chairman, Republican Senator Richard Burr, provided an update on Wednesday of the committee's investigation into activities Russia might have taken to alter or influence the 2016 elections and whether there were any campaign contacts with Russian government officials that might have interfered with the election process.
"There were upwards of 1,000 paid internet trolls working out of a facility in Russia, in effect, taking over series of computers, which is then called a botnet," Mr Warner told reporters on Capitol Hill on Wednesday.
Mr Warner said the committee is investigating to find out whether voters in key states, such as Wisconsin, Michigan and Pennsylvania, might have been served up Russian-generated fake news and propaganda along with information from their traditional news outlets.
"We are in a whole new realm around cyber that provides opportunity for huge, huge threats to our basic democracy," Mr Warner said. "You are seeing it right now."
Mr Burr added that Russians are trying to influence elections in Europe as well.
"I think it's safe by everybody's judgment that the Russians are actively involved in the French elections," Mr Burr said.
The first round of the French presidential election is to be held next month.
Scheduled to appear at the committee's open hearing are: Eugene Rumer, director of the Russia and Eurasia programme at the Carnegie Endowment for International Peace; Roy Godson, professor of government emeritus at Georgetown University; Clint Watts, senior fellow at the Foreign Policy Research Institute Programme on National Security; Kevin Mandia, chief executive officer of the cyber security firm FireEye; and retired general Keith Alexander, former director of the National Security Agency and president of IronNet Cybersecurity.
Pledging co-operation, Mr Burr and Mr Warner said they would steer clear of politics in their panel's probe of Russian meddling.
They made a point of putting themselves at arm's length from the House investigation that has been marked by partisanship and disputes.
Democrats have called for House intelligence committee chairman Representative Devin Nunes to recuse himself because of his ties to the Trump team, especially because the investigation includes looking at contacts that Russians had with Mr Trump's associates.
Republican Mr Nunes met with a secret source on the White House grounds last week to review classified material, which he says indicates that Trump associates' communications were captured in "incidental" surveillance of foreigners.
Mr Nunes said he sees no reason to step aside.
Mr Burr said that so far, the Senate committee has requested 20 individuals to be interviewed.
Five have been scheduled and the remaining 15 are likely to be scheduled within the next 10 days. Additional witnesses could also be interviewed.
Mr Burr identified just one of the witnesses: Mr Trump's son-in-law, Jared Kushner.
The White House has said that Mr Kushner, a senior adviser to Mr Trump, has volunteered to answer questions about arranging meetings with the Russian ambassador and other officials.
Asked whether the committee had spoken to former national security adviser Michael Flynn or his representatives, Mr Burr told reporters: "It's safe to say that we have had conversations with a lot of people, and you would think less of us if General Flynn wasn't in that list."
A lawyer for Mr Flynn said his client had not yet been interviewed by the Senate committee.
One of Mr Flynn's lawyers, Robert Kelner, said they have had discussions with committee staff members, but Mr Flynn has not been contacted directly.
Mr Trump asked Mr Flynn, a former director of the Defence Intelligence Agency, to step down last month from his post as national security adviser.
The president said he made the decision because Mr Flynn had misled Vice President Mike Pence and other White House officials about his conversations with Russia's ambassador to the US.