Navy Secretary John F. Lehman Jr. yesterday assailed the government's plea agreement with retired Navy communications expert John Anthony Walker Jr. for sending "the wrong message to the nation and to the fleet," and said John Walker's promise to divulge details about his espionage activities was not worth the price.

Lehman said he had objected to the arrangement under which Walker pleaded guilty to espionage and conspiracy Monday to gain lenient treatment for his son, Navy Seaman Michael Lance Walker, who also pleaded guilty. John Walker will be sentenced to life in prison while Michael Walker, who also faced the possibility of a life term, will receive a 25-year sentence.

Assistant U.S. Attorney Michael Schatzow, who prosecuted the father and son, reacted angrily to Lehman's comments. "If the secretary of the Navy actually said that you have to wonder why it is that people who are superior to him authorized this agreement if he is right . . . . I think it is worth it, and the people I have spoken to who have spent their entire careers doing intelligence work feel that very strongly, too."

Schatzow said he understood that the plea agreements were approved by Defense Secretary Caspar W. Weinberger and Attorney General Edwin Meese III.

But Lehman said in an interview yesterday: "We in the Navy are disappointed at the plea bargain . . . . It continues a tradition in the Justice Department of treating espionage as just another white-collar crime, and we think that it should be in a very different category." Michael Walker should have received "the maximum sentence allowable under the law," he said.

"Here's a guy at the age of consent who was out on a carrier with 5,500 other kids risking their lives and he was prepared to compromise all of his shipmates, not to mention his whole country, here he was turning over documents knowingly to the Soviet Union," Lehman said.

"One can have a human sympathy for his family situation and . . . his father leading him astray, but nevertheless a human being is responsible for his acts and the acts were traitorous acts and ought to be treated differently than insider trading."

John Walker will be eligible for parole after 10 years, and Michael Walker could be freed after serving a little more than eight years.

Schatzow said Monday that the government agreed to the lighter sentence for Michael Walker, because it was "essential" to learn precisely what secrets John Walker passed to the Soviets in 18 years of espionage.

Lehman said, however, that while the details are "nice to know," investigators already "know the bounds of the problem, we know what he had access to and what he almost certainly compromised, and so we're not going to save any money by what he tells us."

The "only possible payoff," Lehman said, "is if he reveals additional spies. But short of doing that, I don't see that anything he can provide us with is worth . . . the message that is sent."

Shatzow said that "people figured there would be a certain amount of intramural, extracurricular backbiting" after the plea agreements.But, he said of Lehman's remarks, "This is the kind of crap that makes those of us out in the field happy not to be in Washington."

Shortly after the Walkers' arrests, Lehman raised the possibility of having them court-martialed, rather than tried in civilian courts, to ensure that they would be punished severely.

Assistant Attorney General Stephen S. Trott, the head of the Justice Department's criminal division, said at the time that the government would not allow those accused in the espionage ring to "get off light in order to get information from them." Trott was not available for comment yesterday.

Said Defense Department spokesman Glenn Flood, "The Justice Department handled it and they did what I guess they felt was the right thing to do. We are using this to get information."

Meanwhile, prosecutors handling the case in San Francisco against Jerry Alfred Whitworth, the remaining man charged in the Walker case left to stand trial, were in Washington yesterday to discuss prosecution strategy with Justice Department officials. A source familiar with the case said prosecutors were hoping to begin interviewing John Walker, who has agreed to tstify against Whitworth. "I hear they left for Washington before the ink was dry" on the plea agreements, the source said.

Whitworth's uncle, Willard Owens, said he spoke to his nephew Sunday night and "he wasn't upset or excited about" the prospect of having his close friend testify against him.

"I suppose Jerry probably understands why John Walker's doing it, to try to make life more comfortable for himself," said Owens, a wheat and soybean farmer in Muldrow, Okla., Whitworth's home town.

Owens said he did not expect Whitworth to follow the lead of John and Michael Walker and plead guilty. "Why confess to something you absolutely haven't done?" Owens asked.

Lawyers for John Walker's brother, Arthur James Walker, are hoping that the plea arrangement worked out in Baltimore will benefit their client at his sentencing Nov. 12 on seven counts of espionage.

Attorney J. Brian Donnelly said he thought the 25-year sentence for Michael Walker is "a positive sign because it shows that the government is taking individuals into consideration."

He said he believed his client was "much less" blameworthy than Michael Walker. While Michael Walker gave his father stacks of classified documents, Arthur Walker passed only two documents, Donnelly said.

John Walker's daughter, Laura Walker Snyder, who urged her mother to make the telephone call to the FBI that launched the Walker investigation, said yesterday she did not regret that move -- even though her younger brother was implicated in the ring as well.

"If I had known my brother was involved I would have warned him, but I would have continued to do what I planned to do," she said. But Snyder said her brother's sentence was "a great source of pain" to her.

Snyder, whose father tried unsuccessfully to recruit her to join the espionage ring when she was in the Army, she thought he became a spy because, in addition to the money, "he enjoyed the intrigue. I'm sure it wasn't all enjoyable, there was a lot of pressure and stress, but overall he enjoyed the intrigue, the mystery, the fact that he was pulling something off."