Washington ? A senior U.S. intelligence analyst, who confessed to spying for Cuba during a 16-year period, defiantly rebuked American policies toward Fidel Castro as “cruel and unfair” as she was sentenced Wednesday to 25 years in prison on espionage charges.

Ana Belen Montes, 45, refused to formally apologize for her actions, leaving prosecutors disappointed. Montes worked at the Defense Intelligence Agency as one of the Pentagon’s most senior experts on Cuba’s military.

“I felt morally obligated to help the island defend itself from our efforts to impose our values and our political system on it,” Montes told the judge, explaining the motivation behind her actions.

“We have displayed intolerance and contempt toward Cuba for most of the last four decades. We have never respected Cuba’s right to make its own journey toward its own ideals of equality and justice.” she said, reading from a two-page, typed statement.

Prosecutors, who accepted the sentence under a plea agreement, accused Montes of disclosing to Cuba secrets so sensitive they cannot be described publicly. Court records said she provided documents that revealed the identity of four undercover agents, details about U.S. surveillance of Cuban weapons, and information about a December 1996 war games exercise in the Atlantic.

Prosecutors believed Montes

wasn’t motivated by money, since she received only nominal amounts to cover her expenses during her 16 years as a spy. As part of her sentence, Montes, who is single and lived alone, must surrender all her government savings plus interest and any property that investigators could tie to her espionage.

U.S. District Judge Ricardo M. Urbina described Montes’ actions as a “betrayal.” But Urbina complied with a plea agreement between Montes and prosecutors and sentenced her to 25 years in prison, in exchange for her explaining to investigators how Cuban spies operate.

Montes could be released after 20 years with time off for good behavior, according to her lawyer, Plato Cacheris.

Montes pleaded guilty in March to conspiracy to commit espionage, admitting that she revealed to Cuba the identities of four agents. The four are said to be alive and not in prison, but little more is publicly known about them.

Montes, who is of Puerto Rican descent, was believed to have been recruited by Cuban intelligence when she worked in the Freedom of Information office at the Justice Department between 1979 and 1985. She later moved to the Defense Intelligence Agency where by 1992 she was among the DIA’s top analysts on Cuba’s military.

The government has not said what led them to suspect Montes. Court records indicate the investigation began around May 2001, shortly after the government broke up a ring of Cuban agents in Miami known as the “Wasp Network.”