By Duncan Kennedy
BBC News, Mexico City
Startling figures released this week by the United States drugs tsar have hinted at progress in the battle against drugs.
Four tons of cocaine were found in a crashed plane in Mexico
First, the price of cocaine in 37 cities across the United States has risen sharply since March. In some cases it's up by 50%.
Second, the purity of cocaine has dropped by 11% over the same period, indicating the dealers are diluting their dwindling stocks to stretch it further and meet demand.
Both figures were released by John Walters, the top White House official in charge of anti-drug efforts.
"After 25 years of cocaine coming into the United States, there has never been the kind of disruption of this magnitude for this long," Mr Walters said.
Ninety percent of cocaine entering the US comes through Mexico.
Mr Walters was quick to praise the efforts of the Mexican authorities who have, in the past year, taken the fight to the cartels that supply the sought-after white powder.
Since taking office last December, President Felipe Calderon of Mexico has sent nearly 30,000 troops and federal police across his country to battle the drug gangs and disrupt their activities.
After much early scepticism, this approach now seems to be working.
As well as the apparent reductions in the quantities of cocaine making it over the border, major traffickers, like the Arrellano Felix brothers who ran the Tijuana cartel, have been arrested and jailed.
Then there was the arrest last week of the woman known as the Queen of the Pacific, Sandra Avila Beltran. She is alleged to be the mastermind behind the Sinaloa cartel.
Crack cocaine has appeared on the scene in the last decade
There could be more good news soon. Mexico and the United States are finalising a deal that could pump up to a billion dollars into Mexico to equip and train its police force to be even more effective.
Yet Mexico is also paying a price for this battle to keep American cities starved of cocaine.
The move to crush the cartels unleashed a brutal underworld war. It has left as many as 2,000 people dead this year, including about 60 police commanders, 22 soldiers and 160 police officers.
And a trade that once by-passed Mexico is taking root here as well.
The cartels have opened up local markets to avoid risking the improved border security and to take advantage of growing Mexican affluence.
Crack cocaine and Ice (as methamphetamine is known), unheard of 10 years ago, are now the sought-after narcotics by thousands of Mexicans.
The government has been so alarmed by the trend it has just started a programme to test all high school students for drugs.
Walters draws comparisons with the "French Connection" drug haul
As if to underline the continued threat, a plane carrying nearly four tons of cocaine crashed last week in south-eastern Mexico, a sign that the flow of drugs has not yet been completely staunched.
Mr Walters says the greatest benchmark for success was the smashing of the "French Connection" in the 1970s.
That was the breaking up of the heroin supply chain from Europe to New York City.
The operation was so successful that Hollywood turned it into a movie, famous for its violent excesses and car chases.
John Walters is no "Popeye" Doyle, the gritty, unscrupulous detective played in the film by Gene Hackman: someone bent on breaking not only the ring behind the drugs, but also every law and jaw bone that stood in his way.
Instead, he is President Bush's official point man in the effort to reverse years of industrial scale substance abuse.
It is his teams, as well as those south of the border, that can take credit this week for bringing policy success to an area many believed was immune to progress.