Walls are going up all over the world
If good fences make good neighbours, then the world is experiencing an unprecedented outbreak of neighbourliness. They used to wall cities: now they wall whole countries.
India is well on the way to being walled, except along the Himalayas, where the mountains do the job. The barrier along its 3,000km border with Pakistan is largely complete, except in the parts of Kashmir where the steep and broken terrain makes it impossible to build the usual two-row, three-metre-high fence, with concertina wire and mines between the two fences. And India is now building a 3,300km barrier to halt illegal immigration from Bangladesh.
The majority of walls springing up around the world are there to stop either terrorist attacks or illegal immigration, but sometimes they also serve as a unilateral way of defining desired borders. That is certainly true of the 2,700km of high sand or stone ramparts backed by wire fences, mines, radar, troop bunkers and artillery bases that seal off Western Sahara - annexed by Morocco in 1975 - from the camps in Algeria from which many of the former inhabitants waged a guerilla war until the 1991 ceasefire.
It is equally true of the wall that Israel is building through the occupied West Bank. The country has long had heavily mined and monitored barrier fences along its external frontiers with Egypt, Jordan, Syria and Lebanon and around the Gaza Strip, but the wall in the West Bank does not follow the ceasefire line of 1967. Instead, it penetrates deep into the Palestinian territories at several points to leave Jewish settlement blocs on the Israeli side, and it cuts off predominantly Arab East Jerusalem from the West Bank entirely.
Pakistan is building a 2,500km fence with Afghanistan; Uzbekistan has built a fence along its border with Tajikistan; the United Arab Emirates is erecting a barrier along its frontier with Oman; and Kuwait is upgrading its existing wall along the Iraqi frontier. But the most impressive barriers are certainly those around Saudi Arabia.
For several years, the Saudi kingdom has been quietly pursuing a US$8.5 billion project to completely fence its porous border with Yemen. But its highest priority now is to get a hi-tech barrier built along the 900km border with Iraq.
The new wall will include buried movement sensors, ultraviolet night-vision cameras, face-recognition software and quite probably automated weapons in addition to the usual electrified fences, concertina wire, dry moats and mines.
By comparison, the apparently endless debate about building a relatively low-tech fence along the 3,360km US border with Mexico to cut illegal immigration seems like an echo from an innocent past.
The reason that the US is incapable of controlling its Mexican border is political, not financial or technological. Powerful domestic lobbies work to ensure a steady supply of 'undocumented' Mexican workers who will accept very low wages because they are in the US illegally. No equivalent lobby operates in the European Union, and it is only a matter of time before really serious barriers appear on the EU's land frontiers, especially with Russia, Belarus, Ukraine and Turkey.
The walls are going up all over the world, and most of them will not come down for a long time, if ever.
Gwynne Dyer is a London-based independent journalist whose articles are published in 45 countries