To drive into the heart of West Berlin on a dark, snowy night in December 1988 was to descend on to the cinematic frontline of the cold war. Watchtowers manned by armed East German border guards, searchlights, barbed wire, the blackened facade of the gutted Reichstag by the frozen River Spree – it was all there, just like the movies. Yet it was only too real. Holding centre stage: the sinister Berlin Wall. US president Ronald Reagan had made a similar sojourn the previous year. Standing before the Brandenburg Gate, he decried the “vast system of barriers that divides the entire continent of Europe”. If the Soviet leader, Mikhail Gorbachev, really valued peace and freedom, he should act. Like the Hollywood actor he once was, Reagan dramatically declaimed: “Mr Gorbachev, tear down this wall!” Reagan had his wish. In November 1989, under fierce pressure from both sides, the wall imploded. Its end foreshadowed Germany’s reunification and the Soviet Union’s collapse. It was one of those rarest of moments – a genuine historical watershed. Generations who had known only fear and separation felt liberated. Europe was once again made whole. There could be no going back. Or could there? Thirty-plus years later, thousands of kilometres of new walls, security barriers, fences and barbed wire have sprung up in and around Europe. The EU/Schengen area is now surrounded or crisscrossed by 19 border or separation fences totalling 2,048km in length, up from 315km in 2014. Similar trends are discernible worldwide. Everywhere, it seems, new, higher walls are rising. What is so-called “Fortress Europe” afraid of? Historically, walls were built to defend against enemies. Think the Great Wall of China, the Roman Wall, Offa’s Dyke or the Maginot Line. Yet all were eventually circumvented, some easily, some less so. The Theodosian walls of Constantinople were considered impregnable until Ottoman cannon got to work in 1453. The walls of Jericho were blown down by trumpets. No one sensibly suggests a wall, ditch or berm could have stopped Russia’s invasion of Ukraine. Governments claim barriers serve another purpose: deterring transnational terrorism and crime. Yet the real reason walls are back in vogue is primarily political, stemming specifically from Europe’s “irregular migration” problem. Migrant numbers are rising rapidly again – and EU states are in a panic. Latest data from Frontex, the EU’s border and coastguard agency, shows about 330,000 irregular border crossing were detected last year, an increase of 64% on 2021. Nearly 1 million asylum applications were made in EU countries that already host 4 million Ukrainian refugees. More than 71,000 border crossings or attempts were detected in the Channel in 2022. Most would-be migrants came from the Middle East, south Asia and Africa. Such people cannot reasonably be classed as “enemies” notwithstanding the home secretary Suella Braverman’s ugly talk of invasion. Barriers, fences and notional “sea walls”, as attempted by Britain and Italy – and illegal pushbacks, as practised by Greece – are the response of those lacking imaginative, humane answers. Yet many politicians, especially on the right, are pushing the EU to directly fund their ill-considered building schemes. Bulgaria, backed by Austria, wants Brussels to help erect a bigger, better border fence to halt illegal entries from Turkey. Austria has demanded €2bn in emergency cash. Deaf to the irony, Vienna is blocking admission of Bulgaria and Romania to the Schengen “free movement” area. Greece also wants EU help in expanding border walls along a 192km border with Turkey. It says it prevented 260,000 illegal entries in 2022 and arrested 1,500 human traffickers. Poland has built a fence to keep out asylum seekers bussed through Belarus – and has sought EU compensation. Last summer, would-be migrants died trying to storm the barbed-wire fences around Spain’s Melilla enclave in Morocco. Ursula von der Leyen, commission president, argues that encircling the EU with walls and fences offends European values. The European parliament, concerned about pushbacks, detention centres and human rights violations in transit zones, says external border protection must respect EU and international law. But pressure is telling. Last week’s EU summit agreed to provide “substantial funds” to reinforce members states’ “border protection capabilities and infrastructure... including aerial surveillance and equipment”, plus tougher action on visas and returns. Although they will not be directly funded, the divisive walls Europe thought it had consigned to the past are set to proliferate further. Wall-building raises ethical and practical as well as political issues. Far-right politicians have successfully used it to fan fear of foreigners, as in recent Italian and French elections, regardless of whether barriers work or simply force migrants to find other routes. Racist Donald Trump used the spectre of “hordes” of brown-skinned illegals assaulting the US-Mexico frontier to justify his “beautiful” wall – and his nasty prejudices. Yet the wall is ineffective; crossings have not declined. Israeli leaders maintain that their extensive “security barrier” has reduced terrorist attacks from the occupied territories and Gaza. But attacks still occur using rockets, tunnels or infiltration. And what protects West Bank residents from out-of-control Israeli army raids going the other way? Palestinians rightly see Israel’s walls as a means of controlling them and stealing their land. Lengthy fences are increasingly found elsewhere, notably on the India-Pakistan and Pakistan-Afghanistan borders. The Morocco-Western Sahara berm is 2,700km long. These barriers are supposed to fend off military and terrorist threats. But what they mostly do is create obstacles to peace. Often they increase frictions. At best, they freeze enmity in place. The global wall-building boom suggests a return to divisive cold war mindsets. It marks a failure of progressive politics – and reflects the resurgence of authoritarian ideologies of fear, separation and difference. More to the point, geopolitically, ethically and practically speaking, this damaging policy is a dud. Walls won’t work.