Deep within the Pentagon, a small, select group of men and women engage in a continuous, deadly serious game of "Star Wars." Their earnest approach to the game is based on a conviction that the stakes are nothing less than the survival of the United States.

This ultra-secret group of experts has a variety of organizational names. But the generic term is simply the "Red Team," as enemy forces are traditionally designated in military maneuvers. In this case, the name is doubly appropriate, since the Red Team's mission is to play the role of the Soviets in the constant plans and scenarios drawn up in the Pentagon for hypothetical nuclear or conventional conflicts with the Soviet Union.

Who are the Red Team's players? Do they win more war games than they lose against the "good guys" of the Blue Team? Is the computerized war game realistic, or does the Blue Team get unfair advantages in the hope of making President Reagan's Strategic Defense Initiative seem feasible enough to deserve continued funding?

We put these questions to Lt. Gen. James Abrahamson, chief of the Strategic Defense Initiative Organization. The makeup and activities of his outfit are, of course, highly classified, but Abrahamson agreed to lift the veil of secrecy a bit in a recent interview.

He explained that there is not one Red Team, but several, "composed of real experts around this country." Together they may include "dozens of people." But the core is "a small team of about six guys here who manage the process." They rely on full-time experts in the military and the Energy Department (which is in charge of nuclear weapons plants), plus a few staff assistants.

"We have a hierarchy of Red Teams that are put together," Abrahamson explained. "I have a group of people that I call my Countermeasures Team, and they do the organization of this, and they are responsible to make it work."

Countermeasures are a touchy subject for SDI advocates. There's always the chance that the most futuristic weapon can be checkmated by a fairly simple countermeasure. Lasers can be outfoxed by missiles that spin or have highly reflective surfaces. Heat-seeking SDI missile interceptors -- ballistic-speed space bullets -- can be thwarted by missiles with fast-burnout liftoff that shut off before the interceptors home in on them. Sheer numbers of enemy missiles could make a defensive system meaningless if even a small percentage got through to their targets.

There's also a Red Team of Kremlinologists, an "overall kind of Strategic Red Team," as Abrahamson described it. These specialists ask themselves such questions as, "Would the Russians do this kind of thing? How does it fit into Soviet strategic doctrine?"

In a specific scenario, these experts constitute a White Team: "references," Abrahamson called them. They caution the Red Team aggressors when they feel there's doubt that the Soviets would follow a particular course of action.

The Blue Team, Abrahamson said, is composed mainly of SDIO personnel, "but we bring in some others, too, so that they have some perspective, so our guys don't get stuck in a rut too easily."