First the Air Force came to Ely, Nev., in December 1977 to look over valleys south of town as possible sites for the new, giant MX intercontinental ballistic missile.

Then, last month, with Ely now a favorite to base some MX missiles, came the Soviets, dressed in jeans and sport shirts and almost 2,500 miles from their posts in Washington. They identified themselves as Vladimir Kvasov and Vladimir Militsyn. The Soviet embassy lists Kvasov as a lieutenant commander and an assistant military attache and Militsyn as a civilian employe of the attache's office.

Trailing right behind them, and sometimes even a step ahead, were agents of the FBI, also wearing the casual cowboy garb of the area.

That October day the Russians, and the FBI, visited Ely (population 6,500) is one the townspeople will not forget.

It was, moreover, an event that provides a vivid glimpse at one of the sometimes humorous but often serious intelligence games regularly played by the two superpowers.

Military attaches are, in a sense, legal spies. Stationed in each other's capitals, they regularly travel, trying to collect whatever information that might prove useful. And those wanderings are always monitored by the host country's security agents -- the KGB in the Soviet Union and the FBI here.

The day the Soviets showed up, Oct. 4, Irene Carson, the assistant librarian at Ely's public library, was running things because her boss was at a convention.

As she recalls it, two FBI agents arrived at the library before it opened and told her two Soviets with diplomatic immunity would be coming to town on the plane from Elko.

"The Russians were pretty sure to show up" at the library, the agents told Carson, since they had done that the day before at Elko.

Carson was given a description of the men and shown pictures by the FBI agents. They told her to give them everything they wanted, and the agents would return later.

Around 11 a.m., the two showed up, Carson said, "dressed very casual" and described themselves as "travelers from Washington D.C."

The younger Russian went to the newspaper rack, while his friend asked for books "on industry in Las Vegas," Carson said. Las Vegas is out of bounds for Soviet embassy personnel because of its proximity to Nellis Air Force Base and the Nevada nuclear test site.

When Carson told the Soviet that gambling was the one industry in Las Vegas, he said he would browse around the library.

Shortly, however, they both came back with a book "on the Nevada test sites," Carson recalled. The volume was the 300-page environmental impact statement for the Nevada site, where the U.S. government conducts underground tests of its nuclear weapons.

They asked if they could photocopy the book, and Carson told them it would have to be done at the county courthouse.

The older Russian sent his colleague off to do that while he remained at the library telling Carson, as she remembers it, "I'll stay here for security," since books normally are not allowed to be taken from the building by visitors.

His colleague returned some time later to say the courthouse photocopying machine could not be used for such a big job but that he had found a store that would do it, but at a cost of $47.

The expense was approved, and the almost two-hour task began at the nearby store.

Ed Meyer, clerk at the store, said the Russians told him he was "an energy engineer" from Washington who needed the information in the book and was only in town for a little while.Since he was in such a rush, the Russian said he would do the photocopying himself so that Meyer could continue to wait on customers.

Almost immediately after the job was done and the Russian had departed, an FBI agent "dressed like a cowboy," according to Meyer, came in. In a pattern that was repeated at every stop the Soviets made, the agents asked the Ely people to recall exactly what the visitors had said and what they took with them.

Meanwhile, back at the library, the senior Russian attempted to make small talk with assistant librarian Carson.

At one point, "He asked me if I'd ever been to Russia," she said, and later he gave her an illustrated book on SALT II.

When the younger attache returned the library book, the two departed, but not before asking where a local Indian rservation was. About 150 Indians who had lived on a small reservation in town had recewntly moved to new homes some distance away, Carson said she told them.

They left, she recalled, saying they wanted to walk to the old reservation.

When the FBI later interviewed Carson, they asked her to give them the SALT II book, and took it with them.

Another stop for the Russian duo was the White Pine County Chamber of Commerce.

Betty Whitehurst, who manages the office, had been called the night before their arrival "by a local law-enforcement official" and warned of their possible visit because of the pattern of their past activities.

"They gave me their height and age," and told me to treat them as we do all tourists.

When the Russians did arrive, they talked a bit and visited the town's museum, signing in at the register.

From Whitehurst's pamphlet display they took almost every item, including, the Chamber manager laughingly pointed out, "a 9-inch by 9-inch shoplifting placard which warns you can be detained under Nevada law for shoplifting."

"It's very popular with store owners here," Whitehurst said, " because before people could just walk out after being caught and we couldn't do anything about it." She could not explain why the Russians took that item.

Another stop was the White Pine Development Corp., where, according to Mike Bourne, "They asked for general information about the area . . . the kind of industry in the area."

They told Bourne they were from an embassy in Washington, and he quickly spotted them as Russians, despite their Western dress, because, as he put it, "both their first names were Vladimir."

The two had lunch in a local diner and, according to a local newsman, spoke loudly in Russian.

In the wake of the visit, rumors spread as to what had actually taken place in Ely.

The local newspaper, The Ely Daily Times, wrote it up a week later as an item in its column that records town doings -- some of which is just gossip.

The sheriff's office, which provided advance information to some townspeople, said through a spokesman Wednesday that the whole thing never happened.

When a Las Vegas newspaper jumped on the story, Brig. Gen. Guy Hecker, the chief Air Force Spokesman on the MX, said the visit showed the Soviets are concerned about the missile.

He added, "We want them to know as much as possible" about the basing, since the Soviet ability to verify how many of the mobile missiles are in each site is important under SALT II.

The FBI has remained silent about the affair.