(Update: The people of the United Kingdom have voted to leave the European Union in a referendum known as Brexit, short for British Exit. This story has been updated throughout.)

Today, people around the world are reeling from the news that the United Kingdom will withdraw from the European Union and that British Prime Minister David Cameron will resign as early as October. Negotiations about how the so-called Brexit will play out will likely take years. But on Friday morning, it was already causing tumult in the global economy, sending the British pound to a 30-low and S&P 500 futures down more than 3 percent, just as economic experts predicted it would.

But those admonishments did not faze the "Leave" faction advocating for Britain to exit the EU. That's because the same primal fear creating so much upheaval in the current US election is also driving many in the pro-Brexit camp. It's the fear that foreign threats want to infiltrate the UK and terrorize its citizens. The easy access EU member countries have to cross one another's borders, they argued, and it seems successfully so, amplifies that threat.

To truly isolate itself, a country would not only have to stop immigration. It would have to stop information.

Especially given recent terror attacks in Paris and Brussels, the desire of UK citizens to fend off nefarious intruders is understandable. But in preaching the gospel of isolation, both the leaders of the Brexit movement in the UK and Donald Trump here in the US are forgetting a crucial fact: In the age of the Internet, there's no such thing as going it alone.

In many ways, the Internet has turned borders into a technicality. Yes, stricter immigration laws can prevent people from physically moving from one country to another, but they'll never be able to prevent foreign ideologies from spreading online. The web, after all, is worldwide.

"There is absolutely, matter-of-factly, verifiably, no isolation in the world today," says Parag Khanna, author of the book Connectography: Mapping the Future of Global Civilization, which argues that the world is now defined less by countries and more by connectivity. "There is no place in the world you can't get to or that there aren't the modern trappings of technology."

And yet those very ideologies are what Trump and pro-Brexit leaders perceive to be the real threat. Just this week, Trump said he only wants to admit people to the US "who share our values and love our people." Meanwhile, Brexit supporters like Nigel Farage, leader of the UK Independent Party, have campaigned for Britain to leave the EU with ads that show immigrants crossing a border en masse. "Within a few years, all of these people will have EU passports," Farage says in the video below. "We are much less safe as part of this European Union."

But what both Trump and Farage neglect to mention is that so much of the radicalization that happens around the world today takes place online. As WIRED's Brendan Koerner wrote in our April issue, ISIS's social media machine is startlingly sophisticated and essentially impossible to cut off. ISIS's ideology has become, quite simply, a brand, as readily co-opted by international audiences as any other. As Koerner wrote, "Its brand has become so ubiquitous, in fact, that it has transformed into something akin to an open source operating system for the desperate and deluded."

To prevent that system from spreading, a country would not only have to stem the flow of immigration. It would have to stem the flow of information. It would have to stop radical leaders from brainwashing people on Twitter, from rallying followers in YouTube videos, from sharing their hateful ideology on Facebook. In other words the US and the UK would have to follow the lead of a country like North Korea, encasing its citizens in a bubble and blocking their access to a world of knowledge. That's a decision neither country seems prepared to make—nor should they. But by expending so much energy on the perceived threat they can see, Brexit advocates and Trump supporters alike are diverting focus from the very real threat that exists online.

Among the ironies here is that if anyone should be aware of the power of social media to raise the profile of fringe voices, it should be people like Farage, Trump, and Johnson. It is fear-mongering on social media that has helped validate their own extremist proposals. But the bigger issue is that in striving for some idealized detachment from foreign threats, they may only be giving those threats more space to grow. As the UK distances itself from the rest of Europe, what power will it have to ensure that Europe, its next door neighbor, is doing all it needs to do to mitigate risk? What say will the UK have?

To truly protect a country from global threats in a world of pervasive connection, Khanna says, "the answer is that you actually need to be more connected. You cannot influence what you're not connected to."