The plot seems ripped from the pages of a post-Cold War espionage thriller: Russian spy services hack into the Democratic Party's computers, pilfer reams of data and then leak damaging emails in the hopes of helping elect a preferred presidential candidate.
Yet that is exactly the allegation the FBI confirmed Monday it is investigating.
The recent hack of the Democratic National Committee's computers has left U.S. officials scrambling over how to respond to a cyberattack that may have crossed a new line in the secretive world of state-sponsored spying and computer warfare.
One government official equated the hack against one of America's main political parties to an assault on the nation's "critical infrastructure," such as the electrical grid.
The FBI's terse statement confirming the investigation came just three days after Wikileaks published a trove of nearly 20,000 internal DNC emails that showed its leaders privately favoring former Secretary of State Hillary Clinton over her rival, Sen. Bernie Sanders, in the party's primary. The embarrassing emails forced the resignation over the weekend of the party's chairwoman, Rep. Debbie Wasserman Schultz.
But the specter of Russia's involvement has begun to loom larger and is far more concerning to former FBI officials, diplomats and cybersecurity experts who expressed concerns that Russia could be seeking to tip the electoral scales in favor of Clinton's Republican opponent, Donald J. Trump.
Clinton's top campaign officials wasted no time in seeking to deflect attention from the emails' contents to the possibility that Russia might be trying to help Trump. It marked a surprising turnaround since Republicans traditionally viewed Russia, and the Soviet Union before that, with a wary eye, and had frequently accused Democrats of being too soft on America's Cold War enemy.
Even in the 2012 election, Republican presidential candidate Mitt Romney called Russia "our No. 1 geopolitical foe."
Now Clinton operatives are pointing to statements by the business mogul that indicate a break with past Republican orthodoxy, suggesting he would be more lenient in dealing with Russian President Vladimir Putin. Trump has praised Putin's leadership style and said recently that he might not support some NATO allies if they were attacked by Russia, a remark quickly condemned by Democrats and Republicans alike.
Clinton campaign officials have also noted that Trump's campaign co-chairman, Paul Manafort, previously worked as a consultant for the now-ousted pro-Russian government in Ukraine.
At a news conference Monday, Clinton campaign manager Robby Mook cited the assessment of unnamed experts that Russian state actors had facilitated the hacking and release of the emails "for the purpose of helping Donald Trump."
Clinton spokesman Brian Fallon told reporters that "Trump has been espousing in public a bunch of policies from a foreign policy standpoint that would completely play into Vladimir Putin's hands."
The Trump campaign strongly rebutted such allegations. On Twitter, the candidate called the claims "a joke." His son, Donald Trump Jr., told CNN that he could not "think of bigger lies."
In an interview on ABC's "This Week," Manafort denied there were any ties between the campaign and Putin. "That's absurd," he said. "And, you know, there is no basis for it."
Wikileaks has also dismissed claims that Russian hackers provided them with the emails, though they have not said where they acquired them.
Getting to the bottom of whether Putin or the Russian government is behind the hack will be difficult, even if the FBI confirms the findings of CrowdStrike, a well-regarded cybersecurity firm that was hired by the DNC to investigate the hack.
CrowdStrike in June issued a lengthy report "identifying two separate Russian intelligence-affiliated adversaries" as the hackers. One of the hacking groups, believed to be run by the Russian security service FSB, was inside the DNC servers for at least a year; the other, linked to the Russian military, penetrated the DNC systems in April. Neither appears to have known the other was inside the computers.
A number of cybersecurity experts have confirmed CrowdStrike's findings, calling the evidence of the Russian involvement overwhelming.
"There are Russian fingerprints all over this," Rich Barger, chief intelligence officer of ThreatConnect, said in an interview.
Russian hackers are no strangers to U.S. law enforcement and intelligence officers. They are also believed to be responsible for the successful theft of data from the State Department and White House servers.
Robert Anderson, a former top counter-espionage and cyber official at the FBI, said Russian spy services were known for being particularly aggressive and competent.
"They will do everything they need to do to further their agenda," he said, adding that he felt that any attempt to influence an election "crosses the line."
The dilemma for U.S. officials now is how to respond. The U.S. government has taken a variety of actions in dealing with cyberespionage in the past. In 2014, for example, the Justice Department indicted five Chinese military officials on charges of using computers to steal trade secrets from major U.S. businesses and a trade union.
The same year, the Obama administration publicly blamed North Korea for hacking the computers of Sony Entertainment Inc. and leaking emails to humiliate the company.
But it took a more low-key approach in handling a massive hack of sensitive information at the Office of Personnel Management, saying only that China was a leading suspect and later refusing to publicly assign blame on Beijing. That theft was seen within intelligence circles as a more traditional form of spycraft that the U.S. also utilizes.
White House Press Secretary Josh Earnest said Monday the White House didn't yet know whether Russia was involved in this particular hack and would await the results of the FBI investigation before deciding how to respond.
State Department Spokesman John Kirby declined to comment on the DNC hack, adding that "we want to let the FBI do their work before we reach conclusions on what happened and the motivations."
Steven Pifer, a former U.S. ambassador to Ukraine who is now a senior fellow at the Brookings Institution in Washington, said he would not be surprised if it turned out that Russia was responsible for the intrusion and leaking of DNC emails.
"Clearly they would like to see Mr. Trump as president over Ms. Clinton," he said. "Downgrading NATO, undoing treaties, praise for Putin.… What's not to like at the Kremlin?"
But he said it would be difficult for the U.S. to settle on an effective response. Among the options would be to lodge a formal diplomatic protest or perhaps expel Russian diplomats.
Pifer said the most effective retaliation might be to simply make public Russia's involvement.
"The U.S. public wouldn't react too well to knowing of Russian interference" in an election, he said. "Then you might have a big backlash against the goal" of helping Trump.
Times staff writers Christi Parsons and Michael A. Memoli contributed to this report.