Manuel Rocha in 2003, a year after he finished serving as US ambassador to Bolivia.
CNN  — 

Manuel Rocha, the former US ambassador to Bolivia who?acted as a?secret?foreign agent?of?Cuba, was sentenced to 15 years in prison after pleading guilty to federal charges Friday – a judge telling him, “you turned your back on this country.”

Rocha, 73,?pleaded guilty in Miami to one count of conspiracy to act as an agent of a foreign government and defrauding the United States. He also pleaded guilty to acting as an illegal agent of a foreign government without notice to the US government.

Prosecutors have alleged the former American diplomat acted as a “covert agent of Cuba’s intelligence services” for decades.

“I take full responsibility,” Rocha said.

He also told family and friends he was “deeply sorry” for his actions.

Judge Beth Bloom told the defendant: “You turned your back on this country over and over again.”

Bloom sentenced Rocha 5 years for conspiracy to act as an agent of a foreign government and 10 years for acting as a foreign agent to be served consecutively.

Charges for lying to investigators and wire fraud were dropped under the plea agreement.

During the three-and-a-half hour?hearing Bloom suggested prosecutors had not done enough to investigate possible victims. The US government is the only victim, federal prosecutors said.

“For 53 years, information was provided,” Bloom?told prosecutors.?“I don’t know if there are victims. I don’t know if you know.”

Bloom also asked prosecutors why Rocha, a naturalized US citizen from Colombia, was not stripped of his citizenship. Rocha pledged allegiance to the US during a naturalization ceremony in the 1970s while working for an enemy of the state, Bloom said.

Rocha’s citizenship is a “benefit, a privilege, an honor” that was obtained by “fraud,” Bloom said.

“Why was that not important to the United States?” she asked prosecutors.

Assistant US Attorney Jonathan D. Stratton said the government considered stripping his citizenship but prioritized that Rocha admit his guilt.

“We are not making concessions or foregoing the civil division going after denaturalization as part of its case. We are just not mandating it,” Stratton said.

At Rocha’s age, Stratton noted, a 15-year term is tantamount to a life sentence, with little benefit to stripping him of his citizenship when he’s 88.

The plea agreement was then updated to include that the government may seek to denaturalize Rocha in a civil proceeding. It also leaves open a window for newly identified witnesses to seek restitution

At a hearing in Miami in?February,?Rocha?announced his intention to plead guilty, according to the court docket.?Rocha?had?pleaded not guilty?to all charges?earlier that month.

Rocha referred to US as ‘the enemy’

Manuel Rocha, appears during an interview with an FBI undercover employee in Miami, in an undated still image from video contained in a US Justice Department indictment.

Rocha served as the US ambassador to Bolivia from 2000 to 2002 and as the deputy principal officer of the US Interests Section in Cuba in the 1990s. He also worked for the US Embassy in the Dominican Republic in the 1980s as well as the US Consulate in Italy, and he served in different roles for US embassies in Mexico and Argentina.

His role as the political officer at the US Embassy in the Dominican Republic gave him “special responsibility” for Cuba, prosecutors alleged.

Rocha described being “in charge” of what he called the “knock down of the small planes” – which prosecutors believe to be an incident during Rocha’s tenure working for the State Department in Havana when Cuba shot down two unarmed airplanes operated by members of Brothers to the Rescue, a US-based group opposed to Castro’s government, killing four men.

In several meetings with an undercover FBI employee posing as a member of Cuban intelligence, Rocha repeatedly referred to the US as “the enemy” and praised Cuban revolutionary and politician Fidel Castro, according to court documents.

“My number one concern; my number one priority was … any action on the part of Washington that would - would endanger the life of – of the leadership, or the – or the revolution itself,” Rocha allegedly told an FBI undercover employee, according to a recording of a meeting cited in court documents.

CNN’s Hannah Rabinowitz and Katelyn Polantz contributed to this report.