The three were arrested by Kuwaiti authorities on Sunday, spokeswoman Lt. Col. Debbie L. Haston-Hilger said in a statement.
The statement did not say how the smuggling was discovered or identify the men. A local newspaper, The Arab Times, reported that police caught the Americans as they were selling marijuana in the city's downtown, and that they had said they imported the drug through the U.S. military's postal service.
Drugs are banned in this small oil-rich state. Possession of drugs as well as their trafficking is punishable by law. Convicted traffickers face the death penalty.
Kuwait has been an ally of the United States since the U.S.-led Gulf War that liberated it from a seven-month Iraqi occupation in 1991. It was the launch pad of the U.S.-led invasion of Iraq in 2003, and it remains a major logistics base for troops serving there.