There’s nothing new about children travelling alone through Central America and Mexico to get to the United States. The journey and its dangers were portrayed five years ago in the film Sin Nombre. One character, Sayra, a teenage girl from Honduras, ends up crossing the Rio Grande alone. She is looking out for Casper, a friend she made weeks earlier on the Mexico-Guatemala border. He doesn't make it: he’s shot on the river bank by a rival, 12-year-old gang member.

What’s changed since then is a sudden surge in numbers. Unlike adult migrants, most children report to the US Border Patrol once they cross the frontier. In the nine months to June this year, more than 52,000 'alien children' were registered, twice as many as in the previous twelve months. An unknown number have failed to report; died or been attacked on the way; decided that Mexico offers a marginally but sufficiently better life than Honduras, Guatemala or El Salvador; or – most likely – been caught and deported by the Mexican authorities.

Five years ago, fewer than a thousand children headed north from Honduras and made the border crossing; in the last nine months there have been more than 15,000. The city that supplies more migrant children than any other in the region is San Pedro Sula, the most dangerous city in a country with the world's highest murder rate. Buses arrive several times a week carrying women and children deported from Mexico. Everyone agrees that drugs and gangs have fuelled the escalating violence from which they were trying to escape. But there's widespread disagreement about causes and solutions.

Proponents of la mano dura ('the firm hand'), whether Republican US senators or the Honduran president, view it as a security problem that needs more detention centres, faster deportation, firmer borders at all points on the migrant routes and more militarised police forces. Barack Obama has asked Congress for an extra $4 billion to keep the borders secure from children. Hillary Clinton has urged that they be reunited with their families (provided their relatives are not in the US).

Meanwhile, a stronger police force back home will clamp down on the gangs and drugs, and the violence will subside. The US under Bush and Obama has ramped up security spending to levels not seen since the ‘dirty wars’ of the 1980s, in what amounts to the remilitarisation of Central America. In Honduras, police units equipped and acting like armies have been created, with names like the ‘Tigers’. There is even a programme in schools to train children to be 'guardians of the fatherland'.

The counter argument is that it’s no coincidence that, in the five years since the military coup, child migration has grown even faster from Honduras than from Guatemala or El Salvador, while in Mexico it has actually fallen. A combination of corruption, violent repression and impunity means that many Honduran officials are part of the problem, not the solution. Among almost daily evidence, the report of police collusion with the notorious drug trafficker ‘El Pelon’ (‘Baldy’) is only a recent example. UN experts have denounced the police as perpetrators of torture. People who expose official complicity in crime are themselves persecuted. The director of a child protection charity, Casa Alianza, said that the police are indifferent to the recent upsurge in child murders. There was a clumsy attempt to fit him up for crashing into a police car while supposedly drunk.

Nicaragua, even poorer than its northern neighbour, does not feature in the US Border Patrol’s statistics of child migrants. Last year it became the safest country in Central America, with a murder rate one-tenth that of Honduras. Yet it has the region’s smallest police force, the lowest military spending per head and the smallest prison population. Aminta Granera, the region’s only female chief of police, attributes these successes to community-based policing in which young people are imprisoned only as a last resort. The model is the opposite of militarised policing, and goes ignored by Obama and Clinton.