posing a particular threat is the grimy frontier city of Nuevo Laredo, which is linked to Laredo in Texas by a broad bridge across the Rio Grande. Over the past three years, it has been the scene of a bloody turf war between organised crime cartels for control of the mega-million dollar trade in smuggling narcotics into the US. Hundreds of people have been killed, some in battles featuring rocket launchers and grenades: according to the State Department, dozens of US citizens have been kidnapped in Nuevo Laredo.

When I was there a week or so ago, law enforcement officials had captured a notorious enforcer for the powerful Gulf cartel, his father and other gangsters. Eleazar Medina Rojas was paraded in handcuffs for the media, with a cache of drugs, jewellery, communications gear and three gold-painted assault rifles.

As is increasingly the case, the

Eleazar Medina Rojas was paraded with his weapons cache (above, and previous page)

arrest was carried out by Mexican federal police: most local police forces, poorly paid and skimpily trained, are deeply corrupt, often pocketing regular 'wages' from the drug traffickers. On past form, Medina could now be extradited to stand trial in the US, in the footsteps of another drugs baron, Osiel Cardenas, who ran the Gulf cartel.

Although the travel warning acknowledges there is no evidence of Americans being specifically targeted in the top international destination for US holidaymakers - they spent some $11bn last year - it is hardly going to boost the tourist trade. Many Mexicans resent the suggestion that their famously hospitable country is unsafe.

One newspaper cartoon showed the Virginia Tech gunman with a pistol beneath a sign announcing in English: "Warning: Mexico is too dangerous!"