(CNN) -- No one, especially not one of Mexico's top law enforcement officials, denies that killings by drug cartels have reached record levels.



Mexican police carry a body after a clash with gangs that left 21 dead in the state of Chihuahua on February 10.



But Monte Alejandro Rubido Garcia, executive secretary for the National System for Public Safety, has an explanation.



"Mexico all of a sudden stopped being a drug-transit country and became a drug-consuming country," Rubido told CNN on Thursday.



That means gangs that once shipped drugs into the United States are now fighting each other to sell the drugs at home, he said. Their fights center on territory -- who gets to sell what and where.



"The only way to settle their differences is through violence," Rubido said. "They're fighting block by block in a very violent way."



The result is a brutal onslaught that resulted in about 5,400 deaths last year, more than double the 2,477 tallied in 2007. Many analysts say Mexico is on track to set a record again this year.



Former U.S. House Speaker Newt Gingrich called the situation in Mexico a "civil war" on a national TV program a few weeks ago.



Larry Birns, director of the Washington-based Council on Hemispheric Affairs, terms it "a sickening vertigo into chaos and plunder."



The violence also is a result of the Mexican government's stepped-up fight against the drug cartels. President Felipe Calderon's administration has spent more money and confiscated more drugs than any previous one, Rubido said.



"Every time the state strikes a blow against them, their reaction is more violence," Rubido said of the drug cartels.



A United Nations report released this week notes that the "government of Mexico faces violent opposition by drug cartels to its attempts to fight organized crime and drug trafficking," adding that "drug cartels have responded with unprecedented violence."



Much of this violence, Rubido said, is carried out in "high-impact" fashion, aiming to get attention and demoralize the cartels' enemies. For example, decapitations have become common. But decapitation often is not the cause of death.



"They're first killed with a shot, then decapitated for maximum visual impact," the law enforcement official said. "They're trying to make the state go into reverse."



That will not happen, Rubido vowed. "The only way to fight this is like we're doing in Mexico."



He listed three fronts in the conflict: a frontal assault on the gangs; prevention campaigns against drug use; and a common strategy and tactics among Mexico 1,660 police agencies.



It's a tough battle, he admits, especially since the use of cocaine in Mexico has doubled in the past four years. Cocaine traffickers, Rubido said, have been looking for new markets and have targeted Europe and Mexico.  Watch how the violence is affecting the United States »



The U.N. report released this week notes that "despite concrete measures adopted by the government, drug abuse remains high in Mexico, especially among school-age children and young people."



The war on drugs in Mexico is made even more difficult by rampant corruption, the report says.



"There is so much money involved in the drug trade, there is so much fear involved in the drug trade, that no institution can survive unaffected," said Birns.



Says Peter Hakim, president of the Inter-American Dialogue, a Washington-based policy center: "This has really revealed just how corrupt Mexican officeholders are, how many people in key positions in the anti-drug war have been taking money from narcotraffickers."



In one recent instance, Noe Ramirez Mandujano, who was the nation's top anti-drug official from 2006 until August 2008, was arrested on charges that he accepted $450,000 a month in bribes from drug traffickers while in office.



There have been other similar arrests of high-ranking officials for taking bribes from drug traffickers.



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What do officials say? What did the government step up its fight against? Where are drugs being used more? What's the violence also a result of?
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question: What do officials say?, answer: "They're first killed with a shot, then decapitated for maximum visual impact," | question: What did the government step up its fight against?, answer: the drug cartels. | question: Where are drugs being used more?, answer: "Mexico | question: What's the violence also a result of?, answer: Mexican government's stepped-up fight against the drug cartels.