Security experts say there is growing speculation that the Kremlin has been meddling in European politics by funding opposition movements in an effort to weaken NATO and other trans-Atlantic ties.
"The Kremlin's reach into European politics is hardly new, but newly worrying," said Jennifer Harris, a former U.S. State Department policy planning staff member and current senior fellow at the Council on Foreign Relations. "Putin likes to put out his financial tentacles to the political elite in other countries to strengthen his influence."
The contents of thousands of hacked Democratic National Committee emails were made public just before the party's national convention began Monday. Among the emails were indications that the DNC favored the presidential campaign of Hillary Clinton over Bernie Sanders. DNC Chairwoman Debbie Wasserman Schultz stepped down from her job after the leak.
Secretary of State John Kerry raised the issue of the hacking with Russia's top diplomat on Monday, but made no accusations about who was responsible. The FBI is probing the intrusion, however.
Asked by a reporter about allegations that Russia was a behind the hack, Russian Foreign Minister Sergey Lavrov replied, "I don't want to use four-letter words," according to The Associated Press. Russia's state-controlled news media have largely made denials or ignored the allegations altogether.
The idea of Russia hacking a U.S. political party's emails may sound like a Cold War spy novel, but it fits into a larger pattern of how Putin operates.
"It is true that some populist parties in Europe have received funding from Russian sources," said Christopher Granville, co-founder of research firm Trusted Sources and former chief strategist at Moscow-based investment bank United Financial Group.
The strongest example of the Kremlin's effort to buy support was when Marine Le Pen, the far-right leader of France's National Front, accepted financing from Russian sources via a Moscow-based bank.
Putin's reach goes beyond France. Fiona Hill, a director at Brookings Institution, pointed out that Berlin has been concerned about unconfirmed payments allegedly made to right-wing populist parties in Germany, including the Alternative fur Deutschland. But tracking the money trail has been increasingly difficult.
Analysts say Russia's activity in Europe has increased since it was sanctioned economically for its military intervention in Ukraine. The long-standing sanctions continue to derail its economy, despite a partial rebound in oil prices this year.
"Russia has come under economic attack from Europe through sanctions and seeks to bolster political forces in Europe that are more sympathetic to the Russian point of view," Granville said.
Hill agrees. "There is a concerted effort by Putin and the Kremlin to weaken the sanctions regime and to chip away at the individual bases of support of these sanctions," said Hill, who formerly covered Russia at the National Intelligence Council.
There's further speculation, although unconfirmed, that Putin has funded antifracking campaigns in Romania and in parts of Eastern Europe in an effort to guarantee the region's dependence on Russian oil, its main commodity.
"Russia's support (whether financial or simply rhetorical) for European parties and organizations that question the role of the European Union, NATO and the United States is meant to strengthen the forces that challenge the post-Cold War political order and, in this way, advance Russia's interests and increase its influence," said Olga Oliker, senior adviser and director of the Russia and Eurasia Program the Center for Strategic and International Studies.
Russian bankrolling of political groups in countries it sees as opponents is an ongoing threat in the eyes of both Brussels and Washington. Democratic claims that the Russians are to blame for the leaked emails will likely result in a sharper divide between the West and Russia.
The wild card in all of this is if Republican candidate Donald Trump becomes president.
"The idea is that Putin-Trump would be a win-win for the Kremlin, as they have mutual interests and alliances," said Hill.
Trump's questioning of American support for NATO resonates with Putin, who has been aggressively trying to weaken the alliance, Kremlin-watchers say.
Correction: This story was revised to correct a typo in Vladimir.