Former Mexican President Vicente Fox has taken his newfound activism in favor of marijuana legalization to San Francisco, where he joined other legalization advocates to urge the United States to adopt federal laws that would decriminalize the sale and recreational use of the plant.

Fox met for three hours with activists and entrepeneurs, among them Steve DeAngelo, the executive director of the largest marijuana dispensary in California, and former Microsoft manager, Jamen Shively, who is the founder and president of a marijuana company called Diego Pellicer, a brand that is looking for ways to commercialize marijuana.

The former Mexican president told reporters that legalization is the only way to end the violence caused by Mexican drug cartels, which he attributed to the long standing U.S.-led war on drugs. "The cost of this war is becoming unbearable, it's way too high for Mexico, for Latin America and for the rest of the world," he said. According to Fox, 40 people under the age of 18 are killed in drug-related violence every day.

Fox's position on this issue heavily contrasts that of the current Mexican president Enrique Peña Nieto, who has opposed legalization, but he's said to be open to other opinions in the matter, particularly in light of recent initiatives approved by the voters of the United States to legalize marijuana in Washington and Colorado for recreational use.

Fox announced the First International Symposium on the Legalization of Marijuana for Medical Use to take place at the Fox Center in Gunajuato, Mexico from July 18 to the 20 in which participants will push for a global strategy to end the prohibition of marijuana.

Support for the legalization of marijuana in the United States has been increasing during recent years. Nineteen states and the District of Columbia have passed laws approving the medicinal use of marijuana, according to the National Organization for the Reform of Marijuana Laws, however, the drug is still considered illegal at the federal level.

Efforts to legalize the plant for recreational use reached an all time high when Colorado and Washington state both passed laws that allowed the recreational use of marijuana for the first time ever in the United States. The laws will take effect at the beginning of 2014.