After the Iranian government announced last Friday plans to cut fuel subsidies, protests erupted in dozens of locations nationwide. Almost immediately, photos and videos began to be uploaded and shared on social media, showing protesters defying authorities and blocking roads.

Soon after, however, the stream of information slowed to a trickle. First, mobile networks stopped working in parts of the country. Then, suddenly, Iran’s digital ties to the outside world were cut off.

As protests continued, Iranian authorities appeared to have resorted to a move that has become increasingly common among regimes seeking to crack down on protests: They blocked Internet access. The civil society group site NetBlocks, which monitors Internet access worldwide, has observed similar partial or total shutdowns and social media outages in Egypt, Ethiopia, Iraq, Kashmir, Mauritania, Russia, Sri Lanka, Sudan, Venezuela and other countries this year.

For much of the week, Iran’s Internet connectivity was flatlined at 5 percent of usual levels, with the remaining capacity largely used by government servers or regime-aligned news outlets. More than 100 hours after the shutdown began, Internet access still remains largely blocked, even though there was a slight increase in connectivity on Thursday.

Iran’s semi-official Fars news agency quoted a source as saying Thursday that the Internet was “being gradually restored” in some areas.

Connectivity in Iran, Nov. 14-21:

“What this seems to be about is individual’s ability to contact each other, to reach out to families and most of all to tell the world about what’s happening,” NetBlocks director Alp Toker said.

The effect of the shutdown has also risked worsening Iran’s economic crisis, which triggered the protests in the first place.

Reached on the phone Thursday, the chief executive of a Tehran-based start-up company — who was speaking on the condition of anonymity because of the fear of regime reprisals — told The Washington Post that the shutdown was having a severe impact, especially on “start-ups and small businesses.”

Even though companies like his own “have to keep paying salaries, rent, taxes and other daily expenses,” the shutdown has meant that “most Iranian start-ups and online businesses have stopped providing services to people,” he said.

Whoever decided to suspend access, he said, “had little or no sense of how this decision will affect different businesses.”

But at least on a technical level, the move appeared to have been extensively planned. The scale of it, Toker said, is astonishing. Rather than activating a “kill switch," Iranian authorities appeared to have individually cut off separate networks in a “painstaking” effort.

NetBlocks and other groups use a range of methods to track Internet disruptions, including databases of devices connected to the Internet worldwide and the measurement of a country’s IP space. If that IP space shrinks or a large number of devices go offline at the same time and in same region, there is a high likelihood of a deliberate shutdown or accidental outage.

In many cases, Internet disruptions are limited in scale. Amid protests in Venezuela this month, for instance, the country’s state Internet provider curbed access to select platforms during a scheduled speech by opposition leader Juan Guaidó. After the speech, accessibility returned to normal.

Connectivity in Venezuela, Nov. 16:

Meanwhile, protests in Ecuador in October were accompanied by sporadic mobile Internet outages.

Connectivity in Ecuador, Oct. 11-13:

In comparison, the prolonged shutdown in Iran is among the most expansive cases of government crackdowns on protesters’ ability to organize online and communicate with the outside world. It bears a similarity to a crackdown in Kashmir earlier this year, when India suspended access in parts of the disputed region, amid its decision to revoke the region’s special status.

Connectivity in Kashmir, Srinagar and Jammu, Aug. 4-5:

But Kashmir’s population is only a small fraction of Iran’s, and it remains unclear how long Iran — with a population of 81 million — can go without the Internet.

Although most Iranians have been unable to communicate with the outside world this week, some may still be able to access domestic sites via an internal Iranian network that is cut off from the global Internet.

To understand what is happening in Iran at the moment, researchers are also examining potential lessons the recent Internet shutdowns in Iraq may hold. Toker said he and his team had identified certain parallels.

“We have two networks that are technically completely different,” Toker said. “But the mechanisms, the political context and the strategy of shutting off a nation that protests against its leaders ... are reasonable causes for concern,” he said. Iran’s influence on Iraqi politics has been on the rise in recent years, and that has been a key point of criticism among protesters.

Various governments have in the past justified Internet blackouts as necessary to keep public order.

But according to NetBlocks, the Internet shutdowns were in fact closely aligned with spiking death tolls, suggesting that authorities deliberately limited access during potential mass casualty operations, Toker said.

“It really became apparent that this has kind of become a way to trick the world,” he said.

Connectivity in Iraq, Oct. 2-4:

The strong link between the deadly use of force and Internet shutdowns has raised concerns about a rising death toll in Iran, too.

On Tuesday, Amnesty International said that Iran’s security forces may have killed at least 106 protesters. The Iranian government had officially acknowledged only five deaths.

Kaveh Nematipour and Erin Cunningham in Istanbul contributed to this report.

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