A retired US state department official and his wife have admitted spying for Cuba for nearly three decades.
The former official, Walter Kendall Myers, 72, had access to top-secret government information.
Under a plea deal, Mr Myers will spend the rest of his life in jail while wife Gwendolyn, 71, will serve a term of no more than seven-and-a-half years.
She pleaded guilty to a lesser charge of conspiracy to gather and transmit national defence information to Cuba, the BBC reports.
The couple also agreed to forfeit $US1.7 million in assets - including a Washington DC apartment and a large yacht - an amount equal to the total salary he earned from the state department.
They have been in custody since being arrested in June, following an undercover FBI sting operation.
Walter Myers was known as Agent 202, while Gwendolyn Myers was Agent 123, according to court documents.
Shopping trolley swaps
Prosecutors say the couple were recruited three decades ago while living in South Dakota by a Cuban intelligence agent, who had met Myers during his previous role at the state department.
In 1981, the couple returned to Washington where Mr Myers got a job back at the state department and worked his way up.
US authorities say that from 1983 until this year the couple had a shortwave radio to receive messages from the Cuban government.
They also delivered government secrets by swapping shopping trolleys with their Cuban handlers at stores, and spent an evening with then-Cuban leader Fidel Castro in 1995, officials say.
The US justice department said the case should serve notice that America remained vigilant in protecting its secrets.
"For the past 30 years, this couple betrayed America's trust by covertly providing classified national defence information to the Cuban government," David Kris, assistant attorney general for national security, said in a statement.
But the couple's lawyer, Bradford Berenson, said they had acted "not out of selfish motive or hope of personal gain, but out of conscience and personal commitment", reports AP news agency.