FOR most of the 20th century, the small countries of Central America were a backwater, a tropical playground for dictators and adventurers. In the 1970s and 1980s they turned briefly into a violent cockpit of the cold war as Marxist-inspired guerrillas battled US-backed tyrants. Places like El Salvador and Nicaragua generated daily headlines around the world and bitter partisan battles in Washington. When the cold war ended, peace and democracy prevailed and Central America slipped back into oblivion. But its underlying problems—which include poverty, torpid economies, weak states, youth gangs, corruption and natural disasters—never went away.

Now violence is escalating once more in Central America, for a new reason. Two decades ago the United States Coast Guard shut down the Caribbean cocaine route, so the trade shifted to Mexico. Mexico has started to fight back; and its continuing offensive against the drugs mafias has pushed them down into Central America.

Whatever the weaknesses of the Mexican state, it is a Leviathan compared with the likes of Guatemala or Honduras. Large areas of Guatemala—including some of its prisons—are out of the government's control; and, despite the efforts of its president, the government is infiltrated by the mafia. The countries of Central America's northern triangle (Guatemala, Honduras and El Salvador) are now among the most violent places on earth, deadlier even than most conventional war zones (see article). So weak are their judicial systems that in Guatemala, for example, only one murder in 20 is punished.

A collapse in social order, however bloody, is normally an internal matter. Yet it would be wrong to leave Central America to its own unhappy devices. Although the new violence thrives on the weakness of the state in those countries, its origins lie elsewhere. Demand for cocaine in the United States (which, unlike that in Europe, is fed through Central America), combined with the ultimately futile war on drugs, has led to the upsurge in violence. It is American consumers who are financing the drug gangs and, to a large extent, American gun merchants who are arming them. So failing American policies help beget failed states in the neighbourhood.

Reason to worry

The United States is involved in Central America's troubles not just because it helped cause them, but also because it will feel their consequences. By air, Central America is less than three hours from Miami. It is the gringo “near abroad”, a destination for elderly Americans looking for a warm place to retire, though violence will stem the flow. Already the lethal combination of conflict and lack of opportunity is driving thousands of Central Americans to brave the threat of kidnap and extortion to migrate to the United States. More will follow if conditions worsen.

A generation ago, the United States rightly concluded that it had much to gain if the Americas became a community of prospering democracies. Yet it is in Central America that democracy is under greatest threat. The isthmus seethes with ideological polarisation and political mistrust. China is active there. Venezuela's Hugo Chávez is stirring things up. In Nicaragua Daniel Ortega is set to win an illegal third term in an election this year, in part thanks to Mr Chávez's largesse. Honduras saw a coup that ousted an elected, albeit irresponsible, president in 2009. Some Central American countries are doing better: Costa Rica is still one of the safest places in the Americas, for example. But its economic success is based on attracting foreigners as tourists, investors or retired residents. A deteriorating security situation will jeopardise its prosperity—and undermine democracy throughout the region.

Escaping the Hobbesian trap

Central American governments have begun to recognise the scale of the battle they face. But stopping their slide into violent chaos requires many things: reform of the police, prisons and courts; better intelligence and information-sharing; a huge effort to provide more legal opportunities for young men, not least by educating them properly; and more hardware, such as helicopters and patrol boats.

Explore the drugs paradox north of the region with our interactive map of Mexico's traffic routes, "cartels" and violence

All this, of course, will have to be paid for. Central American governments do not collect enough tax revenue to provide the rudiments of a modern state: security, education and health for their people, and transport infrastructure to allow their economies to reap the full benefit of their privileged position close to the United States. Central America has fallen into a Hobbesian trap: the better-off make private arrangements—there are five times as many private security guards as policemen or soldiers in Guatemala, and four times as many in Honduras—and therefore block efforts to levy the tax revenues necessary to strengthen the state. There is a lesson for Central America's governments in Colombia: the tide turned against los violentos only when Álvaro Uribe introduced a wealth tax to pay for a security build-up.

But the Central American governments are not solely responsible for the countries' problems. The drugs policies of the United States are also to blame. And, to cap it all, climate change—to which the unfortunate Central Americans have contributed virtually nothing—seems to be increasing the ferocity of nature in the isthmus. Catastrophic flooding is killing people with increasing frequency, and raising the cost of maintaining infrastructure.

When the guerrilla wars of the 1970s and 1980s ended, Americans forgot about Central America. It is time they remembered it again, and offered some help. They could, for example, lead an aid programme that would tie money for roads, ports and security hardware to increases in the tax take to pay for better security and social conditions.

Such schemes will not, however, solve the fundamental problem: that as long as drugs that people want to consume are prohibited, and therefore provided by criminals, driving the trade out of one bloodstained area will only push it into some other godforsaken place. But unless and until drugs are legalised, that is the best Central America can hope to do.