By DEB RIECHMANN and EILEEN SULLIVAN, Associated Press

WASHINGTON (AP) — Russian experts painted a sinister picture of Russian meddling in the 2016 election Thursday, telling the Senate intelligence committee about fake news, cyber trolls, smear campaigns and even slayings they say could have ties to the Kremlin.

The hearing focused on tactics Moscow is thought to employ in spreading disinformation to influence the opinions of Americans and U.S. policy. There were a few unexpected revelations in the more than four hours of testimony from historians, cyber experts and former intelligence officials.

Sen. Marco Rubio, R-Fla., told his colleagues on the committee that during the previous 24 hours, his former presidential campaign team was unsuccessfully targeted — for the second time — by hackers at an unknown internet address in Russia. House Speaker Paul Ryan also was targeted by internet hackers recently, said Clint Watts of the Foreign Policy Research Institute.

All the witnesses stressed the magnitude of the Russian disinformation campaign not only in the U.S. but Europe as well. Sen. Mark Warner of Virginia, the ranking Democrat on the committee, called it Russian propaganda "on steroids." Committee chairman Sen. Richard Burr said the problem is going to require a global response.

"We're within 30 days of what is a primary election in France. It could be that the Russians have done enough to make sure that a candidate that went to Russia recently, a socialist, made the runoff. We could end up with a pro-Russian government in France," said Burr, R-N.C. "We don't know what the effects are going to be in Germany. But we've actually seen them (Russia) build up a party in Germany."

Eugene Rumer from the Carnegie Endowment for International Peace said the Russian work is not always conducted in the shadows.

"That Russian effort is before us in plain sight — in state-sponsored propaganda broadcasts on RT (Russia Today) in countless internet trolls, fake or distorted news spread by fake news services," Rumer said.

Watts also said no one is talking about the cache of information that Russia still has.

"They hacked 3,000 to 4,000 people. This hacking was pervasive," Watts said, lamenting how the American people have focused too much on the election season hack of the Democratic National Committee. "They have our information" and could use it later for political purposes.

As the hearing got underway in Washington, President Vladimir Putin weighed in from Russia. He dismissed the allegations as "endless and groundless," telling reporters that they are part of a U.S. domestic political struggle.

"This anti-Russian card is being played in the interests of some political forces inside the United States with an aim to strengthen and consolidate their positions," Putin said, without naming anyone.

He also said he is ready to meet President Donald Trump at an upcoming arctic summit.

Watts, who also is a senior fellow at George Washington University's Center for Cyber and Homeland Security, said Trump himself sometimes — apparently unwittingly — repeats propaganda put out by Russian sources. Russian outlets also parrot the president's own remarks, he said. Watts cited three examples when Trump claimed his campaign was wiretapped and his statements that "election is rigged" and "voter fraud" is rampant.

"You can pick almost any of these stories, which have no truth in them, and they show up back in Russian propaganda," Watts said. "What's hard to distinguish sometimes is did the Russians put it out first, or did Trump say it and the Russians amplify it."

Watts said all the Republican candidates, including Trump, were targets of the disinformation campaign.

"If you added it up, I would say it's probably 90 for, 10 percent against" Trump, Watts told reporters after the hearing. "This is out of a three-year snapshot. They (the Russians) were promoting him at such a volume that it drowns out other organic support for the other Republican candidates."

Watts also said he believes that the contents of the Democrats' emails hacked by the Russians and distributed by WikiLeaks were shared ahead of time with state-sponsored news outlets in Russia. They filed their reports before traditional news organizations, he said. "They knew what was in the contents — at least that's what I believe," Watts said.

Kevin Mandia, chief executive officer of FireEye Inc., a cybersecurity firm, said that Russian hackers were constantly evolving their cyber toolkits and have tried to exploit ways to gain access to personal data. Those included ways to bypass what's called two-factor authentication — when users have to enter a separate code, generated by their cell phone, in addition to their passwords to access their account.

Warner focused on disinformation being spread in the final weeks of the campaign through key states such as Wisconsin, Michigan and Pennsylvania. One question he is looking to answer in the committee's investigation is whether Russia would have the knowledge to do this without the assistance of someone with a deep understanding of American politics — a theme he appears to be focused on as part of the committee's investigation.

Sen. Ron Wyden, D-Ore., urged his colleagues to "follow the money" to ascertain Russian connections to the Trump campaign.

Watts, who fears for his own safety for speaking out on Russian activities, urged the committee to "follow the dead bodies." He said Russians tied to the investigation into Kremlin disinformation activities have been killed in the past three months — not only in Russia, but in western countries as well.