President Obama does not have to look as far as Afghanistan to find a drugs war, a failing state and violence that threatens the US’s stability. He can look south to Mexico, to a conflict that is bound to displace far-flung troublespots in US preoccupations.

The deliberate killing of three people with ties to the US consulate in Ciudad Juárez has raised the death rate along the border to a level impossible to ignore in Washington. Six consulates in northern Mexico have sent officials’ families back to the US.

Killings have spread to the “tourist paradise” of the beaches, and north of the border, too; last year, Phoenix, Arizona, was named the “kidnapping capital” of the US.

In the past three years — which have brought at least 18,000 deaths as President Calderón has sent 50,000 armed forces against the drug gangs — the US has treated the violence as a dimension of domestic policy, a worsening of the perennial concerns of cross-border drugs, guns and immigration. The value of that pragmatism is that it treats the violence as a criminal matter, with none of the ideology-soaked rhetoric of the War on Terror.

The downside is that Washington, distracted by the fight against Islamic terrorism, Arizona media have argued, has neglected the rising turmoil and has little coherent to say. Mr Obama has asked Congress for more cash to help Calderón to pay for the armed response, and has received it, building on the programme that George W. Bush put in place, one of the few areas where the two presidents have agreed. Many disagree, however, saying that the military response alone does not have a good record, in Afghanistan or Latin America. But it is justifiable as a first attempt to beat back the lawlessness of the border cities.

Success, however, would need a much wider drive to shore up the courts and police; corruption and intimidation have torn apart any systematic attempt to catch and jail the drugs chiefs. The US can help, with tracking of financial transfers, as well as in border security.

But the violence comes as America’s anti-drugs strategy is floundering; states are inching towards liberalisation but that remains unsayable at a national level. Nor has Washington given enough attention to the growing anti-US mood among governments south of Mexico. Every force of US politics, including the projected rise of its Hispanic population, demands that it put more energy into the Mexican problem in the coming years. Inevitably, it will have less money, troops and attention to spare elsewhere.