ALL THE heavy thinkers are saying that detente is stone cold dead. This time, they tell us, the Kremlin has finally killed it off. Well, maybe so, but I'm not all that sure. I can't help wondering how Ivan feels about all this right now. The Russian man in the street, if there is such a guy.

Because I keep remembering what happened to me one night in the Ukraine, in the old city of Kiev.

It was a long time ago, almost 25 years in fact. I was public relating for the National Association of Home Builders and we had brought a Russian delegation over here to see how Americans lived . . . and, of course, the houses they lived in.

It was one of the first of all those people-to-people exchanges and, most especially, it was a first for me and the 10 Russian builders who shuffled nervously into New York's then-Idlewild Airport that hot June day in 1955. right off the bat, they were all but mobbed by a gaggle of reporters and photographs who thought they were overcoming the language barrier by screaming at the bewildered Russians.

I never did find out what news the press squeezed out of that performance, because I was busy looking for a safe place to stash my Russians until our flight to Washington was called. I located a sympthetic-looking Brooklyn Irish immigration officer who listened to my worries about all those anti-communist New Yorkers who might do bodily harm to my charges -- and me -- if we just wandered around the airport. He volunteered that I could take my Commie friends staight to hell. What's more, he would be happy to help us along. I didn't take him up on it. Eventually, an airline oficial made us a better offer -- safe shelter in his passenger lounge.

That was the start of a 14-city odyssey that lasted for 40 days and 40 nights. Especially nights. Everywhere we went, our builder hosts -- a different group in each city -- felt it was their patriotic duty to throw a monstrous banquet-cum-cocktail party for me and my Comrades. Never mind that the Russians had just spent a long, long day tramping through subdivisions and were still hung over from the previous celebration in the previous celebration in the previous city. Every night, everybody had to toast peace and friendship until the small hours, then briefly to bed before lurching off at daybreak for the next stop, the next subdivision and the next banquet.

A few highlights of that 40-day endurance contest float back to me now: Arriving in Boston late oe evening, I looked out the plane window and saw a huge crowd surrounding the floodlighted field. What publicity, I thought. My bosses will be proud of me. Maybe even give me a raise. Then the cabin door opened and a burly state trooper looked me in the eye.

"You in charge of this bunch?"

"Yessir."

"Well, let's get the hell out of here. There's 5,000 Lithuanians waiting out there. They're madder than hell and they want blood. Yours."

Somehow, we made it to a waiting bus whose driver, luckily, was just as scared as we were. We raced into South Boston with what looked like 200 Lithuanian-packed cars hot on our heels, dashed into our hotel and locked all the doors.

Next day, everything was peaceful. The protesters had to go to work or something and they gave us no further trouble. But even after all these years, I still find it hard to think of Boston as the Athens of America.

Then there was the airline stewardess who was serving breakfast 10,000 feet over the Arizona desert and mistook me for one of the Russians. She figured the only way to get her message across was to repeat the menu three times in the loudest voice she could muster. I kept shrugging helplessly and repeating "Da Da Da" until she gave up and just handed me my tray. As we were deplaning in Tuscon, I congragulated her on her linguistic talents. She gave me a hard look and said softly: "You sonofabitch."

Tuscon was also the place where we were greeted by a cowboy-hatted, gunbelted deputy sheriff who accosted Victor Zegal as we got off the plane. Victor was a second secretary of the Soviet embassy in Washington who made the tour with us and was generally considered to be the security man. Reporters referred to him as "the kindly KGB agent who removes only nine fingernails during interrogation." Victor always denied any police connections, and I was embarrassed for him when the deputy grabbed his hand and boomed out: "Welcome to Tucson. I'm a cop, you're a cop, and I'd be honored to show you around."

Victor grinned shamefacedly and went off arm in arm with his new friend. He told me afterward that his guided tour of Tucson, including the city jail, was a high point of his entire trip. You just never know.

By the time our corss-country hegira wound up in New York, where the Russians were to board ship for a leisurely return via Paris, I had gotten to know all of them quite well and two in particular who did not like their delegation leader any better than I did, and for the same reasons. While they always stoutly denied any knowledge of the English language, they invariably broke up whenever I referred to him as "Ivan the Terrible." Which happened wheneber he and I crossed swords. Which happened often.

On our last night together, my two anti-Ivans and our interpreter joined me in the Oak Bar of the Plaza Hotel folr a farewell drink. There was Comrade Isaaev who hailed from Leningrad and still carried a few pieces of German sharpnel from the historic siege of that city, and Comrade Lysenko from Kiev. They had met for the first time on the flight from Moscow and had become fast friends on the U.S. trip. We reminisced at some length about our travels and I tried to tell them something about America as I knew it. They nodded appreciatively as the interpreter translated.

Then Lysenko spoke up. Slowly, pausing frequently to assemble his impressions, he told me how speptical he had been at the outset when word had come from the Ministry of Construction in Moscow that he had been selected for this privileged visit to America. He had met Americans before World War II, and he didn't think much of them. They were working on a big river dam, and the Americans were in the habit of walking around in their shirt-sleelves, talking loudly. And they always put their feet up on the desk while discussing construction problems with their Russian counterparts.

All in all, said my friend, the Americans he had met seemed a rude, mannerless lot, which he had ascribed to their capitalist upbringing. Lysenko and Isaaev had been seatmates on the flight to the United States, and he recalled how he had assured his comrade that the Americans would try every trick in the book to keep them from learning the real truth about capitalist oppression and warmongering in the United States.

"Boris Ivanovich," he said gravely, addressing me in the Russian fashion as Robert, son of John, "I have been all over your country for more than month and I can't tell the difference between your rich and your poor. All your builders put their feet up on their desks; they all walk around in their shirtsleeves and talk loudly. They are capitalists, but they work hard.

"During the war," he went on, "I was an air force navigator and once was shot down over the Black Sea. After two days and nights in the water, I saw a Russian rescue ship bearing down on me, and I remember I cried out, 'Saved at last!' In a way, that's how I feel tonight about going home to my wife and family. Saved at last.

"But still, I wish I could stay longer, get to see more of your country, to know more of your people.

"We have seen a great deal and learned a great deal in these 40 days: all that wealth, and you use it so well; thousands and thousands of new homes going up all over America. We just don't believe that people who are spending so much wealth on their homes and their families are preparing for war against my country, as we have been told so many times.

"Mr. Isaaev and I are not big shots in the Soviet Union. We won't be able to write our stories for Pravda and Izvestia. But our families and our friends will be waiting for us to tell them what we have seen of America. When we left them in Moscow, they were weeping and wailing because we were going to an enemy country. We would never return. Now we are going home, and you must believe me: We will tell them the truth."

A year passed, and in the summer of 1956, I was in Kiev with an American housing delegation returning the Russian visit. I met against with my friend Lysenko and was introduced to his 16-year-old daughter. A slim, lovely, dark-haired girl, she sat next to me that evening at a performance in the Kiev Opera House. She was quiet as a mouse until there came a loud musical passage on stage. She leaned over an whispered in scarcely accented English: "You must live in a wonderful country. My father has told us all about it."

I felt like jumping out of my seat and shouting, "God Bless America -- and Comrade Lysenko, too." But I restrained myself.

I never saw either of them again. But I've thought of them often.

Maybe detente is really dead and gone, as the pundits are tellung us. Maybe we the people on both sides of the Iron Curtain will never again speak so directly to each other. Perhaps too much has gone wrong: first Hungary and Czechoslovakia, then Vietnam, Poland, Cuba, Cambodia and now Afghanistan.

But when I read and hear today about the death of detente it isn't the men in the Kremlin who come to mind.

I find myself thinking about the girl in the Opera House. And I wonder if she remembers.