On Wednesday, Glenn Greenwald and I revealed new details about the National Security Agency’s efforts to radically expand its ability to hack into computers and networks across the world. The story has received a lot of attention, and one detail in particular has sparked controversy: specifically, that the NSA secretly pretended to be a Facebook server in order to covertly infect targets with malware “implants” used for surveillance.

This revelation apparently infuriated Facebook founder Mark Zuckerberg so much that he got on the phone to President Barack Obama to complain about it. “I’ve been so confused and frustrated by the repeated reports of the behavior of the US government,” Zuckerberg wrote in a blog post Thursday. “When our engineers work tirelessly to improve security, we imagine we’re protecting you against criminals, not our own government.”

That wasn’t all. Wired ran a piece saying that the NSA’s widespread use of its malware tools “acts as implicit permission to others, both nation-state and criminal.” Slate noted that the NSA’s hacking platform appears to be “becoming a bit more like the un-targeted dragnets everyone has been so upset about.” Meanwhile, Ars Technica wrote that the surveillance technology we exposed “poses a risk to the entire Internet.”

In response, the NSA has attempted to quell the backlash by putting out a public statement dismissing what it called “inaccurate” media reports. The agency denied that it was “impersonating U.S. social media or other websites” and said that it had not “infected millions of computers around the world with malware.” The statement follows a trend that has repeatedly been seen in the aftermath of major disclosures from documents turned over by NSA whistleblower Edward Snowden, in which the NSA or one of its implicated allies issues a carefully worded non-denial denial that on the face of it seems to refute an allegation but on closer inspection does not refute it at all.

Prior to publishing our story, we asked the NSA to explain its use of Facebook to deploy malware as part of a top-secret initiative codenamed QUANTUMHAND. The NSA declined to answer all of our questions or offer context for the documents. We went into meticulous detail in our report, which went through a rigorous fact-checking process because of the gravity of the revelations. What we reported, accurately, was that the Snowden files showed how the agency had in some cases “masqueraded as a fake Facebook server, using the social media site as a launching pad to infect a target’s computer and exfiltrate files from a hard drive.” The source for that detail was not plucked from thin air; it was rooted in multiple documents that refer to the technique in action, including the internal NSA animation that we published.

A particular short excerpt from one of the classified documents, however, has taken on new significance due to the NSA’s statement. The excerpt is worth drawing attention to here because of the clarity of the language it uses about the Facebook tactic and the light it shines on the NSA’s denial. Referencing the NSA’s Quantum malware initiative, the document, dated April 2011, explains how the NSA “pretends” to be Facebook servers to deploy its surveillance “implants” on target’s computers: