Colombian President Juan Manuel Santos signed a decree Tuesday legalizing and regulating medical marijuana, the latest softening of the country's hardline tactics in the war on drugs.

"We have just taken an important step to place Colombia at the forefront of the fight against disease, with a decree... that allows licenses to be granted for the possession of seeds, cannabis plants and marijuana, and for the plant to be grown for exclusively medical and scientific purposes," Santos said in a nationally televised address.