BATTLEFIELDS aside, the countries known as “the northern triangle” of the Central American isthmus form what is now the most violent region on earth. El Salvador, Guatemala and Honduras, along with Jamaica and Venezuela, suffer the world's highest murder rates (see map). The first two are bloodier now than they were during their civil wars in the 1980s.

Organised crime is now the main cause of the bloodshed. Central America forms a bridge between Colombia, the world's biggest cocaine producer, and Mexico, which is the staging post for the world's biggest market for the drug—the United States. As pressure has mounted on the mobs, first in Colombia and now in Mexico, Central America has attracted more traffic. Ten years ago it had fewer cocaine seizures than either Mexico or the Caribbean; by 2008 it accounted for three times more than both combined. Over the same period the murder rate rose across the region, doubling in some countries.

“Central America is entering an extraordinarily critical phase” in which its peace and security are threatened by “the onslaught of the drug-trafficking organisations”, an official from the International Narcotics Control Board, a United Nations agency, warned this month.

Much of the blame lies with the arrival of the Mexican mafias, mainly the Zetas and the Sinaloa “cartel”. The assassination of Honduras's top anti-drugs official in 2009 seems to have been a Sinaloa hit. Zeta training-camps and recruitment banners have sprung up in Guatemala. The Mexican mobs are also contracting out their work, taking advantage of Central America's competitive narco-labour market. They recruit trained hitmen from the pool of soldiers laid off by several countries' armies, slashed since the end of the civil wars 20 years ago. Guatemala has cut its army's nominal strength by two-thirds since 1996. Now former members of its notorious Kaibiles special forces are said to have close links with the Zetas, themselves a former Mexican special-forces unit.

See our interactive map of drug-trafficking routes and "cartel" territories in Mexico

Then there are the roughly 70,000 members of Central America's maras, or youth gangs, which provide a ready supply of teenagers willing to ferry drugs, mind kidnap victims and carry out other low-level tasks. The blossoming links between the drug traffickers and the maras are a big worry. “What would happen if the cartels infiltrated and united with the maras? There would be war, as in the favelas [self-built settlements] of Rio de Janeiro,” says Alejandro Gómez Vides, president of the Central American Court of Justice.

Leave aside that nowadays Rio looks peaceful compared with parts of Central America. There are signs this fusion is already happening. In El Salvador the proportion of crimes attributed to minors rose from 5% in 2000 to 12% in 2009, and the number of imprisoned youths more than doubled in that period. Mexican mobs have found the maras to be “fertile ground”, says Aída Luz Santos de Escobar, president of El Salvador's public-security council, a government agency. In the maras they have found “people who don't value life, nor even their own liberty,” she says. The Mexicans' tendency to pay in drugs has pushed up local consumption, offering new opportunities for criminality.

Most Central American governments are ill-equipped to tackle the mayhem. The countries of the “northern triangle” are among the poorest in the Americas, with income per head of around $2,700, less than a third that of Mexico. The $2.1 billion of drugs, arms and cash recovered in Guatemala during the first six months of last year was equivalent to 5% of the country's GDP. Yet despite its poverty, Central America receives little outside help: of the $1.6 billion so far allocated under the Mérida Initiative, a United States drug-fighting programme for Mexico and Central America, Mexico received 84%.

Political instability adds to the difficulties. Nearly all foreign aid to Honduras, as well as intelligence-sharing, was frozen following a coup against its president in 2009. One result has been a rise in drug flights from Colombia and Venezuela to Honduras, according to a report from the Wilson Centre, a think-tank based in Washington, DC. At least 154 such flights were logged in 2009, compared with almost none in 2005. A new government has since restored some of Honduras's international ties, and the flights have tapered off. But some American congressmen want to cut aid until human rights are respected.

Though Central America offers a new base for Mexican traffickers, it could yet be their undoing. Mexico's cartels, now the most powerful in Latin America, began as runners for the Colombians and were paid in product. They promptly seized control of distribution in the United States, and turned the Colombians into mere suppliers. The maras of Central America, which have close ties to inner-city gangs in el norte, could yet pull off the same trick. Roy David Urtecho, Honduras's attorney-general, recently warned that the maras were seeking “to establish themselves as legitimate traffickers instead of street-level thugs”. The battleground in the war on drugs may be about to shift again.