The surveillance whistleblower Edward Snowden has alleged that a 2012 incident that took Syria’s internet offline was caused by a National Security Agency blunder.

In an interview with Wired magazine, Snowden said the elite NSA hacking unit, called Tailored Access Operations, accidentally cut off Syria’s internet while attempting to infiltrate it.

The unit allegedly attempted to install an exploit in the hardware of Syria’s main internet service provider that would have provided NSA with mass access to internet usage, communications and patterns in Syria, where a civil war was developing into an Islamist insurgency, destabilising the Middle East.

Instead of gaining mass visibility into the internet habits of Syrians, Snowden alleged, a glitch took Syria offline.

On 29 November 2012, the analysis firm Renesys reported that 92% of the routed networks providing internet connectivity for Syria, 77 of them, had gone dark.

At the time, the outage was widely reported, including by the Guardian, to have been at the instigation of the Syrian government, in order to destabilise opposition groups.

The cybersecurity company Cloudfare analysed the outage at the time, reporting it to be comprehensive:

Since the beginning of today’s outage, we have received no requests from Syrian IP space. That is a more complete blackout than we’ve seen when other countries have been cut from the internet (see, for example, Egypt where while most traffic was cut off some requests still trickled out.

Cloudfare, and others, suggested that Syria’s state-run telecommunications agency, Syrian Telecommunications Establishment, was the only body with the ability to shut off the entire Syrian internet at once. Cloudfare speculated that the failure was caused by a botched router update.

While we cannot know for sure, our network team estimates that Syria likely has a small number of edge routers. All the edge routers are controlled by Syrian Telecommunications. The systematic way in which routes were withdrawn suggests that this was done through updates in router configurations, not through a physical failure or cable cut.

In his Wired interview, Snowden alleged that the NSA attempted to infiltrate the Syrian internet via a core router at the state internet provider. “But something went wrong, and the router was bricked instead—rendered totally inoperable,” Wired wrote. “The failure of this router caused Syria to suddenly lose all connection to the internet – although the public didn’t know that the US government was responsible.”

Snowden told Wired that it resulted in an “oh shit” moment at the Tailored Access Operations center, where NSA operatives feared the Syrian government would discover what they had done. “But because the router was bricked, they were powerless to fix the problem,” Wired wrote. Snowden told the Wired interviewer that NSA officials joked that should they be discovered, they would blame the outage on Israel.

At the time, the government of dictator Bashar al-Assad, blamed the outage on “terrorists”, while opposition groups fighting Assad suspected his government itself was responsible.

The NSA did not respond to questions about the Syrian outage.