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So we've come to the military base here in Tijuana where there's a press conference

coming in a few moments.

The military is announcing the biggest hall since the deployment of military troops

by President Calderon to fight drug trafficking.

They're showing us this amazing image of tons of marijuana displayed behind the podium

with the general in charge of the operation is about to tell us just how significant this is.

The total quantity of marijuana we confiscated yesterday amounts to 12 tons.

Ladies and gentlemen of the press the personnel of the second military region here in Tijuana

are fulfilling their mission as ordered by the president of the republic and the minister of the things

and their determination that in these war on drugs there is no going backwards.

General Sergio Aponte Polito was triumphant.

This was the largest seizure of marijuana by troops since president Felipe Calderon declared a national war on drugs

just days after taking office at the end of 2006.

More than 25,000 troops were deployed to combat the country's powerful drugs cartels,

3,000 of them to the border city of Tijuana and the state of Baja California.

In this week's assignment for the BBC, can Tijuana escape the shadow of one of Mexico's most powerful cartels?

The Tijuana cartel controls the flow of narcotics from the city of Tijuana,

the world's busiest border crossing to the United States, the single most important market for illegal drugs.

That flow of drugs from Mexico to the United States is worth nearly $14 billion a year

...