June 15, 1992

The Earth Summit, which wound up with predictable fanfare today, has given the world its first real glimpse of the kind of global diplomacy that is becoming possible now that the the cold war is over. But the conference has also shown how difficult negotiating worldwide solutions to worldwide problems is likely to be. For decades East-West tensions made it hard to take joint approaches to challenges affecting all the world's nations, including environmental problems like threats to the atmosphere, population growth, and international migration.

Administration officials say that the first experts to conduct a detailed survey of North Korea's nuclear installations have confirmed that the country has been building a large plutonium-reprocessing plant, but that the inspectors have so far found no evidence that enough nuclear material has been produced to make an atomic bomb. The preliminary findings, expected to be announced in Vienna at a meeting of the International Atomic Energy Agency that begins on Monday, cast doubt on the Central Intelligence Agency's worst-case estimates that the hard-line Communist Government could become a nuclear power within a few months to a year.

Two months after saying that Steven J. Ross's prostate cancer was in remission, Time Warner Inc. announced yesterday that Mr. Ross, its chairman and co-chief executive, had taken an indefinite leave of absence for additional treatment. The news immediately raised questions about when, and if, Mr. Ross, who is 64 years old, would return to the helm of the giant media company. Because Mr. Ross has been working from home since late last year, when he began chemotherapy treatments, and has focused more on strategic planning than day-to-day management, his leave is not likely to have an immediate impact on the company.

Twenty years ago this week, on June 17, 1972, burglars broke into the office of the Democratic National Committee in the Watergate Hotel and set off the political shock waves that finally brought down President Richard M. Nixon two years later. Today the names of the Watergate figures still evoke powerful memories of that turbulent time. Haldeman. Sirica. Dean. Liddy. Almost all are still living and most are still living and most are still active, some in new careers to replace the one broken by scandal. Many questions about the scandal are still alive, too. What were the burglars seeking? Who was "Deep Throat," the source for the explosive disclosures published in The Washington Post? Did Mr. Nixon know a burglary was being planned? And what caused the 18 1/2-minute gap in teh tape of a conversation between Mr. Nixon and H.R. Haldeman three days after the break-in?

Poet Laureate Is Named Mona Van Duyn, whose "Near Change" won a 1991 Pulitzer Prize, was named the nation's sixth poet laureate, the first to be a woman. She succeeds Joseph Brodsky. Page C13. Time Warner Chief on Leave Steven J. Ross, chairman and chief executive of the entertainment and media company, began an indefinite leave of absence to continue treatments for prostate cancer. Page D1.