PHILADELPHIA • An unusual question is capturing the attention of cyber specialists, Russia experts and Democratic Party leaders in Philadelphia: Is Russian President Vladimir Putin trying to meddle in the American presidential election?
Until last Friday, that charge - with its eerie suggestion of a conspiracy drawn up in the Kremlin to aid Mr Donald Trump - has been only whispered.
But the release last Friday of some 20,000 stolen e-mails from the Democratic National Committee's computer servers, many of them embarrassing to Democratic leaders, has intensified discussion of the role of Russian intelligence agencies in disrupting this year's presidential campaign.
The e-mails, released first by a supposed hacker and later by WikiLeaks, exposed the degree to which the Democratic apparatus favoured Mrs Hillary Clinton over her primary rival, Senator Bernie Sanders of Vermont, and triggered the resignation of party chairman Debbie Wasserman Schultz on the eve of the Democratic National Convention's first day.
Proving the source of a cyber attack is difficult. But researchers have concluded that the Democratic National Committee was breached by two Russian intelligence agencies, the same attackers behind previous Russian cyber operations against the White House, the State Department and the Joint Chiefs of Staff last year.
And metadata from the released e-mails suggests that the documents passed through Russian computers. Though a hacker claimed responsibility for giving the e-mails to WikiLeaks, the same agencies are the prime suspects. Whether the thefts were ordered by Mr Putin or just carried out by apparatchiks who thought they might please him is anyone's guess.
On Sunday morning, the issue erupted, as Mrs Clinton's campaign manager Robby Mook argued on ABC's This Week that the e-mails were leaked "by the Russians for the purpose of helping Donald Trump", citing "experts" but offering no other evidence.
Mr Mook also suggested that the Russians might have good reason to support Mr Trump: The Republican nominee indicated in an interview with The New York Times last week that he might not back Nato nations if they came under attack from Russia - unless he was first convinced that the countries had made sufficient contributions to the Atlantic alliance.
Mr Trump has also said he would like to "get along with Russia" if he is elected, and complimented Mr Putin, saying he is more of a leader than United States President Barack Obama. Mr Putin has in turn praised Mr Trump.
But Trump campaign officials on Sunday rejected any links between their candidate and cyber efforts to undermine the Democrats.
"Are there any ties between Mr Trump, you or your campaign and Mr Putin and his regime?" Mr George Stephanopoulos of This Week asked Trump campaign chairman Paul Manafort.
"No, there are not," Mr Manafort replied. "That's absurd. And, you know, there's no basis to it."
One of Mr Trump's sons, Mr Donald Trump Jr, was more definitive, charging the Clinton camp with a smear campaign. "I can't think of bigger lies," he said on CNN.
NEW YORK TIMES