Late Friday afternoon, the US intelligence community made it official: Washington believes Moscow is intentionally meddling in the November US elections.

The claim came in a joint statement from the Department of Homeland Security and the Director of National Security published on the DNI website. The two agencies formally accused Russia of hacking the Democratic National Committee and dumping its private emails to WikiLeaks, which published them just before the Democratic convention in July. The disclosures forced the resignation of DNC Chair Debbie Wasserman Schultz, infuriated supporters of Hillary Clinton rival Bernie Sanders, and cast a pall over the Democratic convention in Philadelphia.

“These thefts and disclosures are intended to interfere with the US election process,” the statement read. “We believe, based on the scope and sensitivity of these efforts, that only Russia's senior-most officials could have authorized these activities.”

That’s strong stuff, and new: Unnamed US officials have spent months hinting that Russia was responsible, but the Obama administration has previously refrained from formally blaming Moscow for the hack (or from wink-nod hinting that Russian President Vladimir Putin and his top aides were involved).

Now that the US has officially leveled the accusation, the move could result in new sanctions on Russian officials — and even affect the US election.

Why this is new — and why it matters

That Russia is responsible for the hack hasn’t really been in doubt for a while, though the Kremlin has steadily denied any involvement. The open-source evidence is about as good as it gets in cyberspace.

"The forensic evidence linking the DNC breach to known Russian operations is very strong," Thomas Rid, a professor at King’s College London who studies cybersecurity, writes in Vice. "The forensic evidence that links network breaches to known groups is solid: used and reused tools, methods, infrastructure, even unique encryption keys."

Russia has meddled in European politics and elections for years, often by deliberately spreading false news articles, but its motivation here isn’t entirely clear. The Kremlin could simply be trying to sow chaos, undermine confidence in the US election system, and embarrass America.

Or it could be actively trying to elect Donald Trump. They did target the DNC, and leak emails that exacerbated tension between Clinton and Sanders supporters. Moreover, Trump has made no secret of his love for Putin and openly espouses policies (like undermining NATO) that objectively further Kremlin interests.

Either way, it’s not something the US government wants to tolerate. So for months now, a debate has been raging inside the Obama administration about whether to go after Russia publicly for it. Some favored publicly attributing the hacks to Russia; others favored some more indirect form of retaliation, like hacking the Russian government right back.

“The internal debate is rife with political and diplomatic concerns, including a fear that acting before November might appear unduly partisan,” the Washington Post’s Ellen Nakashima wrote in early September. “US intelligence agencies are also wary that a public attribution might disclose sources and methods.”

The Obama administration has also been under mounting pressure from lawmakers on Capitol Hill, including from leading Democrats. In late September, Sen. Dianne Feinstein and Rep. Adam Schiff, Democrats with senior roles on their respective chamber’s intelligence committee, released a statement publicly blaming Russia for the hack and calling on Americans to “stand together” against Russian interference.

Clearly, the pro-attribution side prevailed. This opens up the door for more overt punishments of Russia, including imposing a special slate of cyber-related economic sanctions created by the Obama administration in 2015.

So this is a serious escalation on Washington’s part. The question is how Moscow will respond: Will this deter Russia from further interference in the US election, or cause them to go even further?

The impact on the US election

It’s not for nothing that the Obama administration was worried about looking partisan. Whenever they announced that Russia was responsible for the cyberattacks, it would make Trump — who has repeatedly suggested that Moscow wasn’t behind the DNC hack — look bad.

One of Trump’s most memorable missteps happened on precisely this topic, when he called for Russia to hack Hillary Clinton this July.

"Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing," Trump said. "I think you will probably be rewarded mightily by our press."

That went too far, even for many of Trump’s supporters. Speaker of the House Paul Ryan’s office issued a terse statement distancing himself from Trump’s stance: “Russia is a global menace led by a devious thug. Putin should stay out of this election.”

The timing for this announcement is also quite bad for Trump. The second presidential debate is on Sunday. National security-focused moderators Martha Raddatz and Anderson Cooper would have almost certainly pressed Trump about his past comments about Putin and why he appears to be pushing pro-Russian policies. They now have grist for an even more pointed question: Why, Mr. Trump, would Moscow be willing to take the risk of going this far to try to ensure your election?

More broadly, there’s a question of whether Moscow’s retaliation will affect the US election directly. The nightmare scenario is Russia actually hacking US voting computers and altering the vote total.

In the DNI/DHS statement, US officials offered nothing but soothing words.

“It would be extremely difficult for someone, including a nation-state actor, to alter actual ballot counts or election results by cyber attack or intrusion,” they explain. “States ensure that voting machines are not connected to the Internet, and there are numerous checks and balances as well as extensive oversight at multiple levels built into our election process.”

That doesn’t mean that Russia won’t look for — and potentially find — some new way of causing mischief. We’ll find out in the next 30 days.