* U.S. warms to Mexico's drug decriminalization law
* Mexico says law frees it to go after crime cartels
MONTERREY, Mexico, Sept 3 (Reuters) - Washington is closely watching Mexico's recent decriminalization of drugs but respects its neighbor's move as a tool in the fight against drug cartels, two senior U.S. officials said on Thursday.
Mexican President Felipe Calderon last month signed a law legalizing possession of small amounts of marijuana, heroin, opium, cocaine, methamphetamine and LSD for personal use, three years after the country ditched a similar plan under pressure from the Bush administration.
More than 13,000 people have died in Mexico's drug war since late 2006. The escalating conflict appears to have nudged the United States, now under the Obama administration, toward quiet support despite its own prohibitionist federal laws.
"We will take a watchful attitude. It is clearly in the authority of the government of Mexico to pass these laws," U.S. drug czar Gil Kerlikowske told Reuters during a visit of border governors to the northern Mexican city of Monterrey.
Mexico says the new law frees it up to go after major criminal cartels that move billions of dollars of narcotics into the United States, the world's top illicit drug market.
Crushing the cartels, who arm themselves with weapons smuggled from the United States and kill rivals at will on busy city streets, has become a major test of Calderon's presidency as the violence worries investors.
Hooded gunmen burst into a Mexican rehabilitation clinic near the U.S. border on Wednesday, lining up patients before killing 17 of them [ID:nN0252253].
"President Calderon has taken on (the drug cartels) ... using limited law enforcement resources, including the expansion of laws to go after drug dealers, using tools that he didn't have, and that is something that the Obama administration applauds," U.S. border czar Alan Bersin said.
DRUG TOURISM UNLIKELY
The support appears to mark a change in Washington's approach to the drug war.
In 2006, Mexico was close to enacting reforms similar to those that took effect on Aug. 21. Pressure from U.S. President George W. Bush's administration pushed then Mexican President Vicente Fox to veto a bill his own party had written and he had supported. [ID:nL339902]
Kerlikowske said he doubted the new law would provoke drug tourism -- in which Americans would go to Mexico to get high legally -- because it was still difficult and dangerous to buy narcotics from dealers on Mexican streets.
Asked if Washington could learn from Mexico and take the step to allow possession of small quantities of harder drugs like heroin, Kerlikowske said: "It is not something that has been discussed under any circumstances."
Groups lobbying for the reform of U.S. drug policies hope Mexico's law could help ignite a change at home, where President Barack Obama has taken a less confrontational approach to the nation's 35 million illegal drug users.
Obama, who described youthful marijuana and cocaine use in his autobiography, has told Congress to eliminate the sentencing disparity between powder and crack cocaine.
The FBI is no longer raiding state-approved facilities that distribute marijuana for medical purposes. (Editing by John O'Callaghan)
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