Writing in the Sacramento Bee, syndicated columnist David Ignatius issues an ominous warning about the dangers of Russian intelligence:

Roll back the tape to January 1964: America is still reeling from the assassination of President John F. Kennedy, and investigators don't know what to make of the fact that the apparent assassin, Lee Harvey Oswald, lived for three years in the Soviet Union. Did the Russians have any role in JFK's death? At that very moment, a KGB defector named Yuri Nosenko surfaces in Geneva and tells his CIA handlers that he knows the Soviets had nothing to do with Oswald. How is Nosenko so sure? Because he personally handled Oswald's KGB file, and he knows the spy service had never considered dealing with him.

For many spy buffs, the Nosenko story has always seemed too good to be true. How convenient that he defected at the very moment that the KGB's chiefs were eager to reassure the Warren Commission about Oswald's sojourn in Russia. What's more, Nosenko brought other goodies that on close examination were also suspicious -- information that seemed intended to divert the CIA's attention from the possibility that its codes had been broken and its inner sanctum had been penetrated.

The Nosenko case is one of the gnarly puzzles of Cold War history.

It vexed the CIA's fabled counterintelligence chief, James Jesus Angleton, to the end of his days.

And it has titillated a generation of novelists and screenwriters -- most recently providing the background for Robert De Niro's sinuous spy film, "The Good Shepherd."

Now the CIA case officer who initially handled Nosenko, Tennent H. Bagley, has written his own account. And it is a stunner. It's impossible to read this book without developing doubts about Nosenko's bona fides. Many readers will conclude that Angleton was right all along -- that Nosenko was a phony, sent by the KGB to deceive a gullible CIA.

That's not the official CIA judgment, of course. The agency gave Nosenko its stamp of approval in 1968, and again in 1976. Indeed, as often happens, the agency itself became the villain, with critics denouncing Angleton, Bagley and other skeptics for their harsh interrogation of Nosenko. In its eagerness to tidy up the mess, the agency even invited Nosenko to lecture to its young officers about counterintelligence.

It happens that I met Angleton in the late 1970s, in the twilight of his life in the shadows. I was a young reporter in my late 20s, and it occurred to me to call the fabled counterintelligence chief and invite him to lunch. (Back then, even retired superspooks listed their numbers in the phone book. I can still hear in my mind his creepily precise voice on the answering machine: "We are not in, at present. ...")

Angleton arrived for lunch at his favorite haunt, the Army and Navy Club on Farragut Square, cadaverously thin and dressed in black. He might have been playing himself in a movie.

He displayed all the weird traits that were part of the Angleton legend, clasping his Virginia Slims cigarette daintily between thumb and forefinger and sipping his potent cocktail through a long, thin straw.

And he was still obsessed about the Nosenko case. He urged me, in a series of interviews, to pursue another Russian defector code-named "Sasha," who he was convinced was part of the skein of KGB lies. The man ran a little picture-framing shop in Alexandria and seemed an unlikely master spy. I gradually concluded that Angleton had lost it, and after I wrote that he himself had once been accused of being the secret mole, he stopped returning my phone calls.

Bagley's book, "Spy Wars," should reopen the Nosenko case. He has gathered strong evidence that the Russian defector could not have been who he initially said he was; that he could not have reviewed the Oswald file; that his claims about how the KGB discovered the identities of two CIA moles in Moscow could not have been right.

According to Bagley, even Nosenko eventually admitted that some of what he had told the CIA was a lie.

What larger purpose did the deception serve? Bagley argues that the KGB's real game was to steer the CIA away from realizing that the Russians had recruited one American code clerk in Moscow in 1949, and perhaps two others later on. The KGB may also have hoped to protect an early (and to this day undiscovered) mole inside the CIA.

Take a stroll with Bagley down paranoia lane and you are reminded just how good the Russians are at the three-dimensional chess game of intelligence. For a century, their spies have created entire networks of illusion -- phony dissident movements, fake spy services -- to condition the desired response.

Reading Bagley's book, I could not help thinking: What mind games are the Russians playing with us today?