U.S. Sergeant Accused of Passing Secrets to East Bloc : Cold War: The ‘extremely sensitive’ data allegedly included tactical nuclear weapons plans.

An Army sergeant was charged with espionage Thursday for providing “extremely sensitive” Army and North Atlantic Treaty Organization defense secrets, including tactical nuclear weapon plans, to intelligence agents for Hungary and Czechoslovakia from 1985 through 1988.

Sgt. Jeffrey Stephen Rondeau, 29, was arrested in Tampa, Fla., by the FBI on a three-count indictment--the latest development in the investigation of an alleged espionage ring organized in West Germany by former Army Sgt. Clyde Lee Conrad. Germany convicted Conrad of high treason in 1990, characterizing his offense as unprecedented in its seriousness. He was sentenced to prison for a term of life plus four years.

FBI officials said they are continuing the investigation, which one described as “the most complicated and extensive espionage case” ever conducted by the bureau. They said that the inquiry has been aided by the cooperation of confessed spy Roderick James Ramsay, also a former Army sergeant stationed in Germany, who was sentenced to 36 years in prison. A federal judge in Florida said that Ramsay’s sentence was lenient because of his cooperation.

FBI Director William S. Sessions said Rondeau’s “arrest underscores the FBI’s commitment to thoroughly investigate all espionage matters,” a statement that demonstrates U.S. intent to continue pursuing espionage conducted on behalf of former Communist regimes in Eastern Europe.

In March, 1989, U.S. officials said that as many as five American soldiers, including some who had left active duty, were under investigation for assisting Conrad, who was allegedly paid $1.2 million for the spying. Ramsay received $20,000, he said. The indictment against Rondeau did not specify an amount of money that he allegedly received.

The alleged conspiracy, in which Ramsay is said to have given Rondeau a torn dollar bill to use as “a recognition signal” when dealing with others in the plot, took place from at least 1983 through August, 1988, according to court documents.

Like others allegedly involved, Rondeau was stationed with the 8th Infantry division in Bad Kreuznach, West Germany, about 50 miles southwest of Frankfurt, until August, 1987. He is accused of obtaining equipment for the espionage, including photography gear, and of using mail, telephone and a one-way radio link to communicate with other agents.

If convicted, Rondeau could be sentenced to as much as life in prison and fined $250,000.