During a brief court appearance, Hanssen did not say anything.
"We will be filing motions in federal court attacking this indictment," his lawyer, Plato Cacheris, told reporters on the courthouse steps.
Judge Claude Hilton set a trial date in October.
Those secrets allegedly include identifying Soviet agents secretly working for the United States who were subsequently executed and information about satellites, early warning systems, retaliation plans against large-scale attacks and communications intelligence.
Facing what prosecutors call a "mountain of evidence," Hanssen's lawyers are expected to challenge the constitutionality of the death penalty for espionage, which could delay the trial for months, reports CBS News Correspondent Stephanie Lambidakis. The FBI, which is still reeling from the McVeigh files controversy, has been eager for a plea deal to avoid any more embarrassing details from coming out. They also want to know what Hanssen did in the period 1992 and 1999, and only the former agent can fill in the gaps.
With the case heading for trial, the FBI could be asked why it didn't catch Hanssen sooner. In 1997, Earl Pitts, a fellow agent convicted of spying for the Russians, raised suspicions about Hanssen, after learning that he had broken into a colleague's computer. According to Pitts' lawyer, FBI debriefers shrugged it off. The FBI said it had no evidence that Hanssen was a spy.
In the past, the government has avoided espionage trials tha could air national security secrets by entering plea bargains in which people accused of spying would agree to tell authorities details of their activities in exchange for lighter sentences.
According to Hanssen's lawyers, plea discussions stalled because the government would not agree to waive the death penalty in exchange for Hanssen's cooperation.
Congress re-enacted the death penalty against spies in 1994 in response to the Aldrich Ames case. Ames, a veteran CIA officer accused of spying more than eight years for the former Soviet Union, pleaded guilty in 1994 and was sentenced to life in prison.
The government has not sought the death penalty against a spy since the law changed. The last spies executed were Julius and Ethel Rosenberg in 1953.
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