One lawmaker believes Russia’s use of social media to influence last year’s election demonstrated how warfare has moved away from the battlefield and toward the internet.

And the U.S. has been slow to adjust, Sen. Mark Warner, D-Va., said Thursday.

“We may have in America the best 20th-century military that money can buy, but we’re increasingly in a world where cyber vulnerability, misinformation and disinformation may be the tools of conflict,” Warner said at The Atlantic’s Washington Ideas fest produced by Atlantic Media, which is Nextgov's parent company. “What we may have seen are the first tools of 21st-century disinformation.”

As vice chairman of the Senate Intelligence Committee, Warner has helped lead one of the congressional investigations into the Russian meddling in the 2016 election. During a public interview with The Atlantic’s Steve Clemons, he gave updates on the progress of the investigation and stressed the importance of social media companies helping Congress understand the extent of Russia’s involvement.

According to Warner, there are three things the committee knows to be true: Russia hacked both political parties and used that information in President Donald Trump’s favor; Russia attacked but didn’t fully break into the voter registration systems of 21 states; Russia used paid advertising and fake accounts on social media to disseminate misinformation to voters.

The sophistication of Russia’s cyber campaign was “unprecedented,” he said. It was also cheap. Warner said the amount Moscow spent in total influencing the American, French and Dutch elections was about a quarter the cost of building an F-35 fighter jet.

“If Russia’s goal was primarily to sow chaos ... and secondarily elect Mr. Trump, they had a pretty good rate of return,” he said.

While Warner said social media companies have helped the investigation thus far, there’s still more they can do. For instance, though Facebook linked a troll farm in St. Petersburg, Russia, to many election-related ads, he said the company has so far only sought out bad actors who paid for ads in Russian rubles.

“I think the Russian services maybe know how to use dollars and euros,” he said.

Later Thursday, after his committee met with Twitter officials, Warner said the company “showed an enormous lack of understanding” on the seriousness of this issue, CBS reported. He also called the meeting “deeply disappointing.”

The committee has already asked Twitter, Facebook and Google to testify before Congress on Nov. 1.

In addition to reluctant social media companies, another barrier the committee has faced is Trump’s unwillingness to acknowledge any Russian involvement in the first place, Warner said. Without any point of contact in the White House, it’s difficult to lead a governmentwide effort to bolster electoral systems against a future attack.

“Our job is to determine whether there was collaboration or collusion, but equally if not more importantly [to determine] how to prevent this from happening again,” he said.