United Nations, N.Y. — The United Nations these days feels the rejected suitor. It wants to be needed and is ready to respond, but somehow urgent world problems don't come knocking as insistently at the UN's doors as they used to.
''So much of what the UN was brought into being for is now done outside,'' says Trinidad and Tobago ambassador Frank Owen Abdulah, who heads a UN committee that deals with decolonization matters.
B.P. Menon, editor of the UN Chronicle, which monitors developments at the world body, says the UN was conceived as an activist organization. But today, he says, ''at best it has a mediating role. At worst it is a complete irrelevance.''
Few diplomats would go so far as to say all the activities of the UN system are completely irrelevant. But there is growing anguish here at the realization that the UN, set up to resolve international conflicts, is being increasingly bypassed. The demand on defenders of the UN to justify its existence is mounting.
Nowhere is the slippage in the UN's role felt more keenly than in its ability to put peacekeeping forces in place between feuding nations or factions. This has long been considered one of the UN's most impressive achievements.
''Peacekeeping has been the UN's most concrete achievement. Now it has become the most controversial,'' says a UN source close to the peacekeeping operation.
The UN's international forces have kept the peace in such volatile places as Cyprus (between Turks and Greeks) and in Kashmir (between Indians and Pakistanis). During the 1973 Middle East war the then US secretary of state, Henry Kissinger, earlier a critic of the UN, reversed himself and praised the efforts of the UN in trying to end the conflict.
More than that, he was obliged to turn to the world body to provide an essential component in the final peace package: UN peacekeeping troops separating the Egyptian and Israeli forces in the Sinai, and the Syrian and Israeli troops on the Golan Heights.
That 1973 success has only increased the UN's sense of isolation over the latest war in Lebanon. The UN Security Council couldn't halt the war. The Israelis ignored the 7,000-man United Nations Interim Force in Lebanon (UNIFIL), overrunning or bypassing its outposts when they moved into Lebanon on June 6.
Finally, when the war was over, UN peacekeepers were rejected by Israel, and the United States had to arrange an alternative international force to maintain the cease-fire. French, American, and Italian troops moved in, leaving the UN on the sidelines.
The difficulty for the UN is that instead of being the remedy for international crises, as its founding fathers intended in 1945, it has become the victim of them. Thus the UN tends to be dragged down by the great problems of the day rather than serve as a spur to resolving them.
A highly placed UN official, for instance, says that on the key question of the Middle East the UN is ''over a barrel on the Palestinian issue'' because each side believes it is right.
Probably the most explosive issue of all - relations between the superpowers - also casts a chill over the corridors of the UN. According to UN veterans who were around during the headier days of detente, the current rift between the US and the Soviet Union runs right through the heart of the UN and overshadows practically every issue under discussion.
A leading European ambassador says: ''A prerequisite for the survival of the UN is the establishment of minimum cooperation between the Soviet Union and the United States, and the resolve of Western governments and parliaments to make use of the UN as an instrument of major policy.''
The UN's authority is diluted not only by superpower tensions but also by an increasing lack of respect for the UN by small- to medium-power countries. Medium-power defiance of the UN is viewed as something of a relatively new phenomenon, a kind of spreading international lawlessness. Among the examples cited are Argentina in the Falklands dispute and Iran and Iraq in the Gulf war. Two other nations, Israel and South Africa, are seen by many delegates as constantly in defiance of United Nations rulings and resolutions.
In some cases, the UN by its own pronouncements advertises its impotence. An Arab ambassador suggests that in both the Iran hostage crisis and the Falklands war, for instance, UN officials trumpeted their conviction that the UN was within inches of reaching a breakthrough or an agreement. When each mediation attempt failed, however, it only eroded UN credibility further.
To US Ambassador Jeane Kirkpatrick the future of the UN will depend on its ability to shun the radicalism, or the ''negative politicization'' as she defines it, which she sees as permeating the UN system. She contends that this radicalism reaches even into such UN agencies as UNESCO (the UN Educational, Scientific, and Cultural Organization) and the International Telecommunications Union (ITU). The result of such radicalism, she says, is an obsession with attacking South Africa and Israel to the detriment of larger world issues.
Yet there are many ambassadors who are inclined to take a longer view of UN achievements. Narajan Krishnan, ambassador from India, comments: ''Sometimes you feel very frustrated, very enraged, because a resolution didn't succeed.'' But over the long haul, he insists, the UN has scored notable successes.
Ahmed Esmat Abdel Meguid of Egypt echoes this viewpoint. He cites the example of the Law of the Sea, which had the overwhelming support of the international community when it was signed in 1982. Yet back in 1958 when the negotiations first started in Geneva, there was scant hope that many nations could reconcile all their conflicting interests.
Says Olof Rydbeck, now commissioner-general of the United Nations Relief and Works Agency (UNRWA) and former Swedish ambassador to the UN: ''Achievements in the UN context are rarely visible. They consist in movements over the years; a change in concepts.''
These movements, often tedious and often achieved only after exhausting hours of negotiation, have over the years built up a body of international cooperation.
This trend toward some kind of international order is reflected, for instance , in the compiling of global statistics that are universally accepted. These provide, according to Jean Ripert, director-general for Development and International Economic Cooperation, ''a common framework, a common language, a common standard, and a common classification.''
Want to know what the world population is likely to be by the year 2000? Or how much gasoline Afghanistan uses in year? Ask the UN.
Partly because of its efforts to maintain a neutral political posture, the UN , too, has been instrumental in persuading as many as 59 developing countries to overcome religious, racial, cultural, or ideological objections and accept family planning programs.
Similarly, the role of the UN in educating the public has been reinforced within the last decade by a number of world conferences - on topics ranging from the status of women and the disabled to renewable sources of energy. The UN Environment Conference in Stockholm in 1972 gave the cause of conservation and the environment a mighty boost, prompting many governments to set up environmental ministries for the first time.
While many would still agree that the time for rigorous self-examination at the UN is long overdue, there is realization that for all its shortcomings, a flawed UN is better than no UN at all.
Would the world be a more dangerous place today without the UN?
''There's no doubt in my mind that's true,'' says Bradford Morse, head of the United Nations Development Program (UNDP) and former undersecretary general for political and General Assembly affairs of the United Nations.
''Conflicts would have been waged around the world but for the UN with all its tethers. Hundreds of places would be vastly different now if it were not for the UN and the quiet consultation that takes place within its corridors, where some modicum of reason or some modicum of approbation was either extended or denied,'' Mr. Morse added.
To V. Tarzie Vittachi, frequent columnist and UNICEF's deputy executive director for external affairs, the UN's problem is that people don't hear about the UN unless things go wrong. ''If nobody falls down the stairs, nothing gets into the newspapers. They forget the balustrade [the UN] was there to save them.''