[In the following review, Lekachman offers praise for The Cardinal of the Kremlin, which he considers "by far the best of the Jack Ryan series."]

Jack Ryan, the engaging, all-American hero of Tom Clancy's previous spy thrillers. The Hunt for Red October and Patriot Games, is entangled here in the high-stakes battle between America and the Soviet Union over the development of Star Wars. Mr. Clancy, a high-tech freak, permits no doubts about the feasibility of a space shield ultimately capable of rendering nuclear weapons obsolete. He is equally certain that, despite Soviet protestations to the contrary, our adversaries have committed more resources to Star Wars technology than we have.

Many technical obstacles impede the superpowers' progress toward a nuclear-free world in which wars will presumably be fought the old-fashioned way—via retail rather than wholesale slaughter. In order to achieve this balance of power, lasers, mirrors and computer software must operate in flawless coordination. After all, a leaky space shield may be worse than none at all if the enemy missiles that penetrate it provoke retaliatory strikes that are promptly followed by counterretaliation. It is needless to add that the country that masters space weaponry first will enormously enhance its bargaining position.

This is the logic that lies behind The Cardinal of the Kremlin, which is by far the best of the Jack Ryan series. In it, Mr. Clancy cuts back and forth from the United States to Moscow, from Pakistan to Afghanistan, touching down at various other locales in between. Nevertheless, it is always clear where we are, since the adventure on which Mr. Clancy sends us is of high quality. And while his prose is no better than workmanlike (the genre does not, after all, attract many budding Flauberts), the unmasking of the title's secret agent, the Cardinal, is as sophisticated an exercise in the craft of espionage as I have yet to encounter

According to Mr. Clancy, the Russians and the Americans each lead and lag in some aspects of the exotic Star Wars technology. Both sides deploy their finest scientists and engineers in search of solutions to problems so intricate only genius-class I.Q.'s can comprehend let alone solve them. The American ace is a certain Maj. Alan Gregory, a 29-year-old graduate of West Point who is the author of a doctoral dissertation on high-energy physics that is immediately classified Top Secret. Awed colleagues compare him to Stephen Hawking and Freeman Dyson. Like his Soviet opposite number, Col. Gennady Bondarenko, Gregory is devoted to achieving his country's technological primacy.

Research of the sort that Gregory and Bondarenko conduct is all very well, but theft can yield results a lot quicker. The American spy in the Kremlin, who is entrusted with this chore and who has been passing important information to the C.I.A. for three decades, is a highly decorated hero of World War II, the Great Patriotic War in Soviet parlance. His opposite number in America, who operates undercover for the Soviet Union at the laboratory where Gregory does his research, is a neurotic lesbian. Another of America's human assets turns out to be a man called simply the Archer, a heroic leader of the Afghan resistance who directs an assault on a Soviet research center that is temptingly close to the Afghan border.

Mr. Clancy keeps his readers well abreast of current politics and psychological theories as well as the latest technology. Part of the intrigue of the novel concerns the intricacies of power struggles within the Kremlin, where a character who resembles Mikhail Gorbachev does battle with an intractable ideologue modeled on Yegor Ligachev, the Soviet leader's second in command. A document very much like the Intermediate-Range Nuclear Forces treaty waits to be signed. An unreformed K.G.B. perfects the sensory-deprivation torture pioneered by Len Deighton in his 1963 novel, "The Ipcress File." And when American special forces are compelled to mount a "wet operation" in order to rescue Major Gregory from Russian agents, they fly in a psychiatrist to cope with the trauma that is induced by killing another human being. (Although this latter is a pleasant conceit, Mr. Clancy does not always come up with believable plot twists. In one of the less credible episodes, for example, his hero, Jack Ryan, lectures no less a personage than the Soviet General Secretary on the superiority of space shields over old-fashioned MAD—Mutually Assured Destruction.)

Mr. Clancy's publisher recently announced that he has signed a multi-book contract. I look forward to each one of the volumes yet to come, not least because their appearance will testify to Jack Ryan's continuing success in averting the next world war.