How can Mexico stop the drugs massacres?

Seventy-two bodies were found in Northern Mexico onTuesday, the result of the latest drug cartel massacre.

The figures are shocking in themselves, but they are becoming less unusual.

In the last four years 28,000 people have died as a consequence of Mexico's drug wars. And increasingly there are suggestions the drug barons are infiltrating the Mexican state.

Some in the United States are now describing it as their country's biggest National Security issue.

The Mexican ambassador in London Eduardo Medina-Mora told Newsnight it might be time to reopen the debate about the legalisation of drugs, although he warned that may open problems of its own.