EUROPE will soon have more physical barriers on its national borders than it did during the Cold War. The ongoing refugee crisis, combined with Ukraine's conflict with Russia, saw governments plan and construct border walls and security fences across the continent in 2015. On September 15th Hungary completed a fence along its border with Serbia, a major point of entry for refugees making their way into the European Union (EU) last year. Within hours, over 60 people were arrested for attempting to scale it. Hungary’s is just one of a ring of anti-migrant fences along the southern fringes of the EU’s visa-free Schengen zone. To the north, in late December, platforms at Copenhagen's Kastrup rail station were fenced off as part of Sweden's latest effort to control the number of migrants entering Malmo from Denmark across the Oresund bridge. Not all of Europe's barriers are so fresh, refugees are still trying to climb or swim around fences originally built in the mid-1990's enclosing Spain's Moroccan enclaves of Ceuta and Melilla. Fences were also erected on Greece's and Bulgaria’s borders with Turkey in 2012, and Ukraine began sealing off its border with Russia in 2014. Last year the Baltic states announced they are following suit. That would leave Belarus's as the only unsealed border between the Baltic and the Black sea.

Since the fall of the Berlin Wall, over 40 countries around the world have built fences against more than 60 of their neighbours. The majority have cited security concerns and the prevention of illegal migration as justifications. More than 30 of those decisions were made following 9/11, 15 of them last year. In the Middle East, the wars in Iraq, Afghanistan and Syria as well as the associated wave of refugees have prompted most countries to close borders. When it completes its border-wall with Jordan, Israel will have surrounded itself entirely. In Asia, too, walls and fences have proliferated, generally designed to prevent illicit movement of people and goods rather than to seal disputed borders, though Kashmir's line of control at India and Pakistan's disputed northern boundary remains a highly-militarised example.

Some proposals for border fences are less plausible than others. In 2013 Brazil announced a "virtual" wall, monitored by drones and satellites, around its entire, nearly 15,000 km- (9,000 mile-) long border. It began work on the Paraguayan and Bolivian sections this year, which are hot-spots for smuggling. But sceptics point out that much of Brazil’s border runs through rainforest that is impassable and hard to monitor. Even given easier terrain, high-tech border security often fails. The United States, which has several times fortified its border with Mexico, and Saudi Arabia, which has shuttered five of its borders since 2003, have struggled with proposals that were either too expensive or didn't work (or both). For most countries, barbed-wire or electric fences, combined with ditches and buffer zones, are the reality. Thankfully, in contrast with the Cold War, transgressors of Europe’s new borders are no longer shot.