In addition, President Obama said in a memorandum released by the White House Thursday Venezuela, Bolivia and Myanmar have "failed demonstrably during the previous 12 months to make substantial" progress in the war on drugs.
There are now 22 countries on the trafficking list, with most of them in Latin America. The U.S. government estimates as much as 90 percent of the cocaine shipped from Colombia each year flows through Central America. Obama said the United States is working through the newly created Central American Security Partnership to thwart the drug trade in the hemisphere.
The memo notes illegal drug trafficking is increasingly being channeled from South America to West Africa before the drugs make their way to Europe and the United States.
Afghanistan remains the largest grower of opium poppies, but production has been cut by one-third in Helmand province, the largest poppy-growing region in the country, the president said in the memo.
While Canada was not added to the watch list, the memo said it is a "significant" source of some illegal drugs.