UN General Assembly session: long on rhetoric, short on results?

Frustrating. Confrontational. Unproductive. This is what many senior diplomats here predict for the 36th General Assembly of the United Nations, which is just getting under way here.

Possible US isolation may be a leading feature of this session. This would give the Soviet Union diplomatic room to manuever, Western diplomats fear.

In any event, the US position is going to be carefully watched by friends, foes, and neutrals alike.

If the Reagan administration's repeated snubs to the international community (stalling the Law of the Sea Treaty; reviewing the approach to rich-poor talks on economic issues; taking issue with the rest of the world on the question of baby milk formula) are an indication of how it will speak and act at this General Assembly, tempers may well flare.

Acrimonious debates between East and West, as well as between North and South , could result.

"With the return to the Cold War that we are watching, with the growing polarization among the nonaligned nations which run for cover behind one of the other superpower, with renewed tensions in the world at large, the United Nations has been placed on a holding pattern," says one analyst.

Many delegations feel they are caught in the middle of a shift in balance between the two superpowers, which destabilizes the political environment and leaves them with little room for maneuver.

Namibia, the Western Sahara, Afghanistan, Cambodia, the Israeli-Arab conflict , remain high on the UN agenda but little or no movement is expected by well-informed sources to take place at the UN on these issues.

Votes condeming once more the Soviet Union and Vietnam for their continuing presence in Afghanistan and in Cambodia are expected. The UN General Assembly has already voted this session 77 to 37 with 31 abstentions to continue seating the representatives of the Khmer Rouge regime. But the vote represents more the continuing opposition to Vietnam's presence in Cambodia than any approval of the Pol Pot group.

On the Western Sahara, some progress has been achieved mainly through the good offices of the Organization of African Unity. A plan has been devised by a group of African "wise men." Its implementation still poses many problems, but no inflammatory verbal clashes involving Morocco, Mauritania, Algeria, the Polisario, and other concerned parties are expected to take place.

Israel will be harshly denounced and the fact that the General Assembly is being presided over by an Iraqi, Ismat Kittani (even though he is widely respected at the UN as an able and moderate professional) is not looked upon favorably by the Israelis.

Naturally, attention is being focused on the Haig-Gromyko meeting this week in New York but no one in the diplomatic community here expects these talks to yield much.

Therefore, the "first act" of the General Assembly, as the period between now and the Oct. 22 summit meeting of 22 chiefs of state in the Mexican town of Cancun is being described, could well be marked by repeated and heated East-West skirmishes.

The "second act," beginning after Cancun and stretching up to the end of December, could be filled with angry denunciations of the North, and more specifically of the US, by the developing nations.