MIAMI | A retired State Department officer and his wife who are accused of spying for Cuba appear to have avoided capture for 30 years because their communications with the Caribbean island were too low-tech to be detected by sophisticated U.S. monitors.
Longtime State Department intelligence researcher Walter Kendall Myers, 72, and his wife, Gwendolyn, 71, were arrested this month after a weeks-long sting operation in which they told an FBI agent posing as a Cuban intelligence officer that they received orders from Cuba's intelligence services over shortwave radio, according to a Justice Department affidavit.
U.S. intelligence spends little time combing the shortwave bands for secret, nefarious transmissions, said James Lewis, director and senior fellow for the Technology and Public Policy Program at the Center for Strategic and International Studies in Washington.
"I'm not surprised [the U.S. intelligence community] missed this," Mr. Lewis said. "We don't put an emphasis on monitoring this kind of activity."
Shortwave radio is a remnant of an era that existed before the Internet and satellite communications, including the sophisticated eavesdropping equipment of the National Security Agency.
But Chris Simmons, a former Cuba analyst for the Defense Intelligence Agency (DIA), said Cuban intelligence still likes to use shortwave to communicate with its agents in the United States.
Former DIA senior analyst Ana Montes, arrested in September 2001 and convicted of spying on behalf of the Cuban government, also received her orders in shortwave communiques. So did Jennifer Miles, who in the 1960s was the last State Department official before Mr. Myers to be arrested on charges of spying for Cuba.
"While some countries have moved to computer-based communications [for clandestine operations], Havana still largely relies on shortwave broadcasts," Mr. Simmons said.
The International Amateur Radio Union said there are more than 700,000 amateur radio operators in the United States.
Though shortwave operators are required to have licenses to transmit in the United States, many do not, said one shortwave user, adding that used equipment is readily sold online.
The Justice Department affidavit said Cuban intelligence appears to have sent the Myerses an unknown number of messages since the late 1970s, using simple number-to-letter codes.
"If you broadcast short messages and are disciplined, you are going to get away with it," Mr. Lewis said.
Even if U.S. authorities detect a transmission and determine that it is a coded message from a foreign intelligence unit, they do not know for whom the message is intended, Mr. Simmons said.
"When an intelligence agent broadcasts from Havana, the footprint it puts down on the earth is hundreds of miles across," he said. "And so from an investigative standpoint, it's impossible to find out who it went to."
Just 50 to 100 watts, about the power needed to illuminate a light bulb, can broadcast a shortwave message halfway around the world, said Moe Thomas, a broadcast television engineering technician in Washington and a shortwave radio enthusiast.
Shortwave radio is considered a "robust backbone system" that works when "all other means of communication are down," Mr. Thomas said, noting that shortwave transmissions have been useful for disseminating information after natural disasters.
Many foreign embassies and U.S. agencies in Washington have shortwave antennas on their roofs, and the news broadcasts of the federally funded Voice of America reach some of the most remote corners of the world via shortwave radio.
A short numerical cipher broadcast from Cuba can easily go unnoticed among the many shortwave transmissions filling the airwaves.
Mr. Simmons said Cuban intelligence uses its U.S. agents to monitor military movements and gather other information and then puts it up for sale.
"The view from Havana is that U.S. intelligence is a commodity that is to be bought, sold and traded to anyone that can come up with the right offer," he said, claiming that Havana told Iraqi leader Saddam Hussein about the type of equipment and forces the United States was using ahead of the Persian Gulf War and the Iraq war.
"Havana has a very keen understanding of where our weak spots are ... and they exploit them," Mr. Simmons said.
Efforts to contact officials at the Cuban mission in Washington for comment were unsuccessful.