It's becoming the trademark move of failing regimes: silence your critics and cripple their communications by cutting off the internet. Libya did it. Egypt too. And last week, Syria pulled the plug on its own internet system.

According to new research from network monitoring company Renesys, it could just as easily happen in many other countries too, including Greenland, Yemen, and Ethiopia. Sixty-one of the world's countries have just one or two service providers connecting them to the rest of the internet.

"If you're a sufficiently small place it's almost inescapable that there will be so little internet that it's almost trivial to turn it off," says James Cowie, chief technology officer with Renesys.

On the other extreme, more than 30 countries – including the U.S., Canada and the Netherlands – have over 40 network providers each at their electronic frontiers. They're almost impossible to unplug.

Renesys came up with its map of the internet's most easily unplugged countries by studying the Border Gateway Protocol (BGP) tables stored in the memory of the big routers used by hundreds of internet service providers. These BGP tables tell the routers how to hop messages from one network to another, and once you start putting together four or five hundred of these tables, you get a pretty clear picture of how the internet is wired together.

So what makes for a easily un-switched country? "It's a high degree of centralization and a low degree of diversity," Cowie says. "They tend to be places where naturally or organically though history or through regulation, the number of providers that get to exchange traffic with their foreign counterparts is very, very low."

So Greenland fits the mold. "Greenland probably wishes it had more diversity, but just the nature of Greenland and the expense of getting connectivity into Greenland means that they're limited to a small – apparently very small – set of providers," Cowie says.

Interestingly, though, Afghanistan does not.

According to Cowie, the Afghanistan once had a countrywide network. It wasn't great, but when it was destroyed in the war a new network formed like a kind of scar tissue over the country, connecting different regions to Iran, Pakistan, Uzbekistan, and Turkmenistan.

"Afghanistan, in the middle of them, buys internet connectivity from all of them," says Cowie. "So the government in Kabul is not any more capable of turning the internet off than they were of building an internet in the first place."