WASHINGTON — A federal judge ordered a former State Department employee and his wife held without bond, saying there appeared to be insurmountable evidence that they spied for Cuba.

At the request of federal prosecutors, U.S. Magistrate Judge John Facciola agreed today to hold 72-year-old Walter Kendall Myers and his wife, 71-year-old Gwendolyn, in jail pending a trial.

Facciola said that there was a risk the pair might try to flee the United States and said that Cuba, moreover, would have a powerful motivation to help them. The Cuban aim, the judge said, could be to reward the Myeres’ reported 30 years of service, to encourage other Cuban agents working in the United States and to prevent the couple from cooperating with U.S. authorities.

“The defendants’ hostility to the United States and their admiration for Cuba is well documented,” the judge said in his ruling. “It is hard to imagine, with so much at stake, that they would feel any compunction to fleeing prosecution in a country to which they seem to feel such little loyalty.”

“To put it bluntly, the government’s case seems at this point insuperable,” Facciola wrote in an order issued shortly after a half-hour hearing summarizing evidence against them.

Prosecutors told the judge that the Myerses talked to an undercover FBI agent about how they would like to sail “home” to Cuba one day, since no travel documents would be needed, and that they dreamed of living on their boat near the island.

Assistant U.S. Attorney Gordon Michael Harvey said the Myerses are experienced sailors with a 37-foot yacht at a club outside Annapolis, Md., and the last entry on a calendar found at the couple’s home showed they planned to go sailing in the Caribbean in November, with no return date. Investigators searching their home also found sailing charts for Cuban waters, a travel guide to Cuba and a book titled, “On Becoming Cuban.”

“The Myerses, if they are able to get back to Cuba, are a real and present danger to the United States,” Harvey said. He said there would be no way for the United States to extradite them from a country it does not have a diplomatic relationship with, or even from the Cuban interests section located just a nine-minute drive from their Northwest Washington apartment.

“The Myerses would be greeted as heroes there,” Harvey said. “They would not be coming back.”

U.S. authorities say the Myerses delivered government secrets to Cuban agents over the past 30 years using a shortwave radio, by swapping carts at a grocery store and in at least one face-to-face meeting with former Cuban leader Fidel Castro in Cuba. Prosecutors say they told the undercover FBI agent that hand-to-hand exchanges of information were the most secure, while talking on the telephone was their least favorite.

They said that in the year before he retired in 2007, Kendall Myers viewed more than 200 intelligence reports regarding Cuba, even though his responsibility was for European matters. Prosecutors said Myers would memorize classified information or take notes that he stored in a safe in his home office so that he wouldn’t have to actually remove documents.

If convicted on all charges, Harvey said sentencing guidelines indicate the Myerses would face 17 years in prison. He said the investigation is ongoing and they could face even more charges.

Facciola agreed that was strong justification for holding the pair. “These defendants have already retired and are each over 70 years old,” he wrote. “If convicted, they face incarceration for what may very well be the rest of their lives. That fate provides a most compelling motivation to flee and avoid it at all costs.”

The couple was seated next to each other at the defense table in a packed courtroom, wearing matching blue jail jumpsuits with white T-shirts underneath. They did not speak or show emotion, and their attorney Thomas Green only briefly argued that they should be allowed to return home with a monitoring device so that they could be with their four children.

Green declined to comment outside the courtroom, except to say, “We’re going to keep plugging along” toward the next hearing scheduled for June 17 before U.S. District Judge Reggie Walton.

Harvey said key evidence in the case came from an undercover operation involving an FBI agent who approached Kendall Myers on the street on the defendant’s birthday, April 15. The agent gave Kendall Myers a cigar, said he knew his Cuban handler and asked that they meet later.

The ruse worked, and the Myerses met three times with the agent at Washington hotels over the next two weeks. Harvey said they made many incriminating statements about their time as spies, and that the sessions were secretly videotaped and audio recorded.

The Myerses were arrested last Thursday when they showed up for what they thought was a fourth meeting.

Harvey said the Myerses told the FBI agent that they were recruited by the Cubans in 1979 and that Kendall Myers was known as Agent 123 and Gwendolyn Myers went as Agent 202.

The prosecutor also said Kendall Myers told the undercover agent he got a job at the State Department at Cuba’s direction and that when asked whether he shared information classified as more than secret, Kendall Myers replied, “Oh yeah, oh yeah.”

Harvey said their statements were backed up with evidence, including a shortwave radio found in their sixth-floor apartment that they said they used to communicate with their handlers about drops, signals and clandestine communication techniques. Authorities also reported finding a diary that Kendall Myers kept professing his admiration for Cuba and Castro, travel records and e-mail communications with “Peter Herrera,” which they had said was the cover name for a Cuban intelligence official in Mexico who they worked with.

Harvey said Kendall Myers wove a “web of deceit” over the years, by making a series of false statements to the State Department about who he was.

“The Myerses have demonstrated with their own conduct they are not worthy of this court’s trust,” Harvey said.

Harvey argued that not only do the Myerses have classified information memorized, they said they would be willing to share what they know about being spies. Harvey said Gwendolyn Myers proposed to the FBI agent that her husband could be an instructor at a Cuban intelligence academy.

“So when can we come?” Harvey quoted her as saying. Harvey said Kendall Myers added, “That I could see doing. That I would like to do.”