Up on the boardwalk though, machine gun wielding members of Mexico´s elite federal police force pulled over cars for random inspections, stopped city buses and checked ID´s.

More than 250 people were executed here last year as this sweltering Pacific resort transformed into the latest battleground between rival cartels battling for supremacy of the multi-billion-dollar drug trade.

After what experts called a decade of paralysis, corruption and inefficiency, President Felipe Calderón has sent 20,000 military and federal troops to six states to confront the drug cartels.

It remains to be seen whether Calderón´s operations, the defining action of his young administration, will restore law and order or are a publicity gambit, as his critics allege.

What is more clear is that as the war between the Matamoros-based Gulf Cartel and the Sinaloa Cartel plunges into its third year, Mexico has passed into a stage of violence unprecedented in the nation´s modern history.

BRAZEN KILLINGS

Police are gunned down inside their own headquarters, the executions videotaped by gloating hit men; traffickers are decapitated, their heads spilled across dance floors as warnings; federal legislators are sprayed with bullets; and beach resorts have become militarized zones.

"The Mexican state wasn´t ready for this war," said Jorge Chabat, a Mexico City analyst who specializes in criminal justice. "The narco-traffickers have traditionally lived in their own dimension, with their own laws. Now we´re seeing them leaving, like ghosts leaving a haunted house."

Drug violence is nothing new in Mexico - what´s extraordinary is the extreme violence of recent months.

Luis Astorga, a sociology professor at Mexico City´s National Autonomous University, says the Gulf Cartel, with its armed wing of former army officers known as Zetas, has accelerated the levels of destruction.

"It´s part of the psychological war, which they learned in the counter-insurgency while they were in the military," he said. "They´re killing machines without ethical brakes."

Few expect Calderón to dismantle the cartels, or even seriously weaken them.

"He´s trying to establish a minimum of order," Chabat said. "He´s sending a message that someone is in charge."

Calderón has earned praise from the White House for his firm stance against the cartels, and for extraditing some top drug lords, including Osiel Cárdenas, who was running the Gulf Cartel from prison.

At home Calderón faces criticism from those who think he´s using the anti-drug operations to inject his presidency with popular support and legitimacy after last year´s controversial razor-thin election.

And the operations are seen widely as a stop-gap - the Mexican government has neither the manpower nor money to keep them going indefinitely.

The operations have so far met with mixed success. Even critics acknowledge that soldiers have brought order to some far-flung pockets that have long existed beyond the rule of law. And while experts warn it´s too early to tell, it seems as though the blistering pace of drug killings - more than 2,000 in 2006 - have slowed since the military was unleashed.

At the same time, a government report says the cartels remain intact and executions have spread to previously violence-free areas.

Echoing a common sentiment, Acapulco bar manager Ulises Olivera calls the military operations a Band-Aid.

"It´s like the cockroach effect," he said on a recent afternoon. "The true narcos just went to other states. When (the military) leaves they will be back. Everyone knows that."

And in some cases the traffickers seem to have been emboldened by the federal operations.

In Acapulco, traffickers targeted officials in early February, just days after federal forces fanned out across the city. Gunmen dressed as soldiers penetrated a local police station, killing seven and videotaping the massacre.

Experts say the fight has gotten so brutal because the stakes are so high: control of an estimated US$142 billion-a-year drug trade. "Whoever wins can assert their self as the arbitrator and can impose the rules of the game nationally and internationally," Astorga said.

TOP OF THE HEAP

Mexican cartels have emerged as the undisputed lords of drug trafficking in the hemisphere with the downfall of the Colombian cartels in the late 1990s.

They have been detected throughout Central and South America and U.S. officials believe Mexicans now control distribution within the United States as well.

Alliances among the top four cartels - the Sinaloa Cartel with the border-based Juárez Cartel and the Gulf Cartel with the Tijuana Cartel - have made it largely a two-sided struggle.

In the past, drug lords have recognized that extreme violence attracts international attention, which is bad for business.

Former drug lord Amado Carrillo Fuentes reportedly brokered an agreement between rival cartels in the 1990s to protect business, and some think it´s possible the current military operations may spur a similar agreement.

"That´s what Calderón is hoping for," Chabat said. "But it can´t happen if one cartel sees the other as weak."

Otherwise, the cartels will continue to make war until a victor emerges from the ashes.

The seeds of the current crisis may have been planted, perversely, with the downfall of the once almighty Institutional Revolutionary Party, or PRI. Not only did the party hold the presidency for 71 straight years, but controlled nearly every state and municipal office until 1989.

Although a barely disguised dictatorship, the PRI´s power allowed it to exert a certain level of control - some would argue tolerance - of organized crime.

"When this was modified, there was a reconfiguration of the political map," said Astorga, who is writing a book about the relationship between the drug cartels and the decline of the PRI. "There were short circuits everywhere."

In the resulting political free-for-all, the traditional ties to the state were cut, giving the cartels more autonomy.

And the struggle for political control between the three leading parties left a power vacuum that allowed the cartels to run amok, Astorga argues.

Mexico´s challenge is to find a way to control drug violence now that it has shed the old authoritarian system.

Calderón is pushing for reforms aimed at diminishing corruption within law enforcement agencies. He wants to create a single national police force and a DEA-style anti-drug unit to replace the current, mostly compromised, forces.

Previous President Vicente Fox gets much of the blame for what many call a flawed, and strangely slumberous, strategy against the drug cartels.

Fox targeted high profile drug leaders, like Gulf Cartel leader Cárdenas, but seemed unprepared for the chaos and reprisals that resulted.