Special counsel Robert Mueller’s indictment two weeks ago of 13 Russian trolls has been viewed as a landmark in the Trump-Russia investigation — but perhaps for the wrong reasons.

While the indictment provides unprecedented clarity about Russian efforts to sway the 2016 presidential election to Donald Trump, it is equally significant as a testament to the US government’s ability to penetrate an overseas adversary — an observation that continues to resonate among followers of the probe.

Mueller discovered the Russians’ names, employment histories, job titles, and internal communications.

He learned that the internet “specialists” in Moscow worked day shifts and night shifts stoking rancor in the US, that their monthly budget was $1.25 million, and that they created a “United Muslims of America” Facebook group to undermine Hillary Clinton.

When Aleksandra Krylova and Anna Bogacheva flew to the US on June 4, 2014, Mueller’s team figured out that they visited Nevada, California, New Mexico, Colorado, Illinois, Michigan, Louisiana, Texas, and New York to gather intelligence before returning to Russia on June 26, 2014.

And they knew that employee Irina Kaverzina destroyed evidence because they read her Sept. 13, 2017, email to a relative saying that “the FBI busted our activity” and that she’d been “preoccupied with covering tracks.”

“That should scare the bejesus out of anybody connected to the Trump campaign who committed malfeasance or is considering being anything other than 110% truthful when they talk to investigators,” said Alan Rozenshtein, a former attorney in the Justice Department’s National Security Division who specialized in cybersecurity and foreign intelligence.

Mueller has not disclosed how he got inside the Internet Research Agency, the Russian troll farm whose election meddling included interactions with unsuspecting Trump campaign workers. He indicted 13 Russian employees, including Yevgeny Prigozhin, an oligarch close to Russian President Vladimir Putin and the operation’s financier.

Some details in the indictment had emerged last October in a major investigation by the Russian news outlet RBC, which identified, for example, the Internet Research Agency's links to a Twitter account, @TEN_GOP, something that Mueller also detailed.

But the indictment contains so much additional information that one former senior government official has complained that it could give Russians a road map to avoid detection of their cyber mischief. “The indictment might reveal something about US intelligence collection methods that will make it easier for Russians to hide their tracks in the future,” Jack Goldsmith, a former Defense Department general counsel, wrote in a blog post. “It will definitely educate other US adversaries.”

Retired CIA officer John Sipher, who was deputy of the CIA’s Russia program in the early 2000s, said seeing that level of detail in public was startling. If it came from intelligence collection, Sipher said, it would be classified.

“It’s not unusual to collect this information,” Sipher said. “But it’s unusual for it to be out in public, for sure. You don’t usually get it declassified and put it into a public document.”

Experts familiar with evidence collection say Mueller likely tapped into enormous communications archives maintained by internet companies such as Google, Facebook, and Twitter, and gained access through laws that require companies to turn over records.

“The thing that is not sufficiently appreciated is that the evidence of all of the crimes in the world has become digitized and is largely in the hands of American technology companies. They are de facto intelligence companies. Internet companies are doing the NSA’s work now,” said Andrew Keane Woods, an expert in cybersecurity and international law at the University of Kentucky College of Law.

The NSA is the National Security Agency, which collects hundreds of millions of emails and other electronic records.

According to a partially declassified 2011 opinion of the court that oversees foreign intelligence collection, the NSA collects an average of 228 million internet communications per year “directly from Internet Service Providers.”

“The first move for investigators is often to go straight to internet companies, which have profiles about all of us that reveal an enormous amount of information,” Woods added. “They are sitting on a treasure trove of evidence for all kinds of investigations.”

The global dominance of US internet companies would have been a huge benefit to Mueller. The companies are subject to US laws that require them to give records to the government in response to a legal order. And they have records from internet users around the world.

Less clear is the legal strategy Mueller would have used to get the records.