She promised to step up US efforts to prevent guns from flowing south from the US to Mexico and to work to address illegal drug demand in both countries, a key underlying cause of the crisis.

About 18,000 people have been killed nationwide in incidents surrounding the narcotics trade in the past four years – more than 4,000 in Ciudad Juarez alone since 2008.

High-level delegation

The weight of the delegation - including Robert Gates, the defence secretary; Mike Mullen, the chairman of the joint chiefs of staff; and Janet Napolitano, the homeland security secretary - underscored Washington's concern over the drug violence south of its border.

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That concern sharpened after the shooting dead of two US consulate employees in the violence-wracked Mexican border city of Ciudad Juarez earlier this month.

The attack raised the question of what Washington could do to bolster security without being seen as interfering in Mexico's internal affairs.

The US is already deeply involved in Mexico's struggle with drug gangs and has pledged some $1.4bn over three years in a thus-far unsuccessful effort to crush cartels which ship $40bn worth of illegal drugs north each year.

Barack Obama, the US president, said last year that Washington had to take its share of responsibility to end the drugs trade, with a large demand for drugs coming from US citizens.

But Mexican critics say the US has not done enough to help and that aid already pledged has been slow to arrive.

Patricia Espinosa, the Mexican foreign minister, said the US team had promised on Tuesday to speed assistance and resolve "bottlenecks that have delayed the delivery of equipment we need".

'Long-term measures'

Al Jazeera's Marina Sanchez, reporting from Mexico City, said people there were questioning how the new efforts would improve the situation.

"What analysts are saying is that these measures may be for the long term; months to be implemented, maybe years to be effective.

Mexico's drug war

 Some 18,000 people have been killed since Felipe Calderon launched a war on drug cartels in 2006.

 Tens of thousands of Mexican soldiers have been deployed around the country to fight drug cartels.

 Mexico is the main supply route for illicit drugs entering the US.

 US state department estimates 90 per cent of cocaine consumed in the US travels through Mexico.

 US and Mexican officials are reviewing the Merida Initiative - a $1.6bn programme to fight organised crime in central America.

"In the meantime, what people in the front line of this war are saying is 'what happens to the civilians, those who every day are living in dangerous places where civilians, even children, are being killed every day?'"

Napolitano said Mexico could expect more US drug enforcement, border security teams, sniffer dogs, licence plate readers and better intelligence sharing, but said Washington also wants to broaden the primarily military focus of the effort.

Eric Olsen at the Mexico Institute at the Woodrow Wilson Centre in Washington, DC, said there seemed to be a some rethinking of the American strategy.

"[In the past] the emphasis was much more on hardware and equipment, the transfer of airplanes. helicopters, x-ray technology, dogs, and other kinds of technology to combat trafficking," he told Al Jazeera.

"I think the realisation now is that simply deploying the army, simply deploying airplanes, is not really going to be a solution to this very difficult and intractable problem.

"There has to be a much more complex and broad approach to it that includes improvement of the rule of law of Mexico, better efforts to reduce consumption of drugs in the United States, better efforts to disrupt the flow of weapons from the US to Mexico and the money that goes along with it."

Mexico is the main supply route for illicit drugs entering the US, with about 90 per cent of cocaine consumed in the US travelling through Mexico.

Social programmes

Clinton said an emphasis on social programmes was important in the wake of the financial crisis that left many on both sides of the border with few economic options.

"The recent downturn in economic growth and remittances has aided the drug traffickers in their recruitment of young people," she said.

Mario Gonzalez Roman, a security consultant in Mexico City, told Al Jazeera that the problems associated with drug trafficking in Mexico would not stop unless the drug consumption in the US is tackled.

'"When is American society going to stop inhaling cocaine or injecting heroine? Unless this comes to a stop, we can't think in terms of progress.

"What we have is here at the centre of the table is a bunch of good intentions but as long as the American government and the American society understands that as long as they don't stop consuming these drugs, the problem in Mexico is never going anyway."

Felipe Calderon, the Mexican president, has added 50,000 troops to the fight against the drugs trade since 2006, but some critics have said that this has only inflamed the conflict's mortality rate.

Calderon recently visited Ciudad Juarez to launch programmes including new schools, nurseries and soccer pitches, aimed at attracting youths away from drug cartels.