A retired US State Department official and his wife have been charged with spying for the Cuban government over a 30-year period.
Washington DC residents Walter Myers, 72, and Gwendolyn Myers, 71, are accused of conspiracy to hand over classified information to Cuba, serving as an illegal agent for a foreign government and wire fraud.
State Department spokesman Philip Crowley said the arrests were the culmination of a three-year joint investigation with the department's security service and the FBI.
The couple could face up to 20 years in prison if found guilty.
The Washington couple were arrested on Thursday after an undercover FBI sting operation having allegedly passed on secrets for decades to Washington's Cold War foe via shortwave radio and in shopping carts.
If found guilty, Mr Myers, allegedly known as Agent 202 by Cuban intelligence officials, and his wife, allegedly Agent 123, face a maximum of 20 years in prison.
Mr Myers first began working for the US State Department in 1977 as a lecturer at the department's Foreign Service Institute in Arlington, Virginia.
A scan of his computer showed that from August 2006 until his retirement in October 2007 Myers had viewed more than 200 sensitive or classified intelligence reports on Cuba, which has been under a US embargo since 1962.
The couple would allegedly get encrypted messages from Cuba via shortwave radio, and Gwendolyn Myers, who worked as an analyst at a local bank, would pass on information to her contacts by exchanging shopping carts in stores.
Mr Myers told the undercover FBI agent that he usually smuggled information out of the State Department by memorising it or by taking notes.
