A former American diplomat, Victor Manuel Rocha, was arrested Sunday and is accused of spying for the Cuban government in what Attorney General Garland called “one of the highest-reaching and longest-lasting infiltrations of the United States government.”

An American ambassador to Bolivia between 2000 and 2002, Mr. Rocha, was charged Monday by federal prosecutors at the Southern District of Florida. 

Prosecutors allege that “for over 40 years, Victor Manuel Rocha served as an agent of the Cuban government and sought out and obtained positions within the United States government that would provide him with access to non-public information and the ability to affect U.S. foreign policy,” according to Mr. Garland.

“Those who have the privilege of serving in the government of the United States are given an enormous amount of trust by the public we serve,” Mr. Garland said in a statement. “To betray that trust by falsely pledging loyalty to the United States while serving a foreign power is a crime that will be met with the full force of the Justice Department.”

In a filing, prosecutors describe a career of spying between 1981 and 2022 that saw Mr. Rocha rise through the ranks of public service. Between 2006 and 2012, Mr. Rocha also served as an advisor to the commander of the American Southern Command, which oversees American military operations in an area including Cuba, and as an employee of the National Security Council.

Prosecutors allege that Mr. Rocha kept his status as a Cuban agent secret in order to allow himself to participate in further clandestine activity and to protect himself.

Some of the actions Mr. Rocha took to protect himself, according to prosecutors, include traveling outside America in order to meet with Cuban officials and intelligence operatives, falsifying travel documents, and providing false information to American officials.

Over the years, Mr. Rocha worked for America at the embassies in Mexico, the Dominican Republic, Argentina, and Bolivia. Mr. Rocha also served at Havana, in 1997.

In 2022 and 2023, an undercover FBI agent reached out to Mr. Rocha, claiming to represent “your friends in Havana.” The agent later met with Mr. Rocha, posing as a covert Cuban intelligence representative. During these meetings, Mr. Rocha admitted to the FBI agent that he had worked for Cuba more than “40 years” and referred to America as “the enemy.”

“Like all federal officials, U.S. diplomats swear an oath to support and defend the Constitution of the United States. Acting as an agent for Cuba — a hostile foreign power — is a blatant violation of that oath and betrays the trust of the American people,” the FBI director, Christopher Wray, said in a statement.

Officials on Monday charged Mr. Rocha with conspiring to act as an agent of a foreign government, acting as a foreign agent, and using a passport obtained by false statement.

After leaving the Department of State, Mr. Rocha began a second career as a businessman and worked at a Dominican Republic gold mine, a Pennsylvania coal exporter, a cannabis merger company, and a Spanish public relations firm.