Secretary of State Alexander M. Haig Jr.'s marathon negotiations to resolve the Falkland Islands dispute underscore the rigidity of both the Argentine and British positions.
As Mr. Haig's talks with Argentine President Leopoldo Fortunato Galtieri and Foreign Minister Nicanor Costa Mendez continued for a third day Sunday, the search for the narrow middle ground between those positions remained elusive.
Following 12 hours of virtual nonstop talking Saturday,April 17, an exceptionally well-informed source said early Sunday:
''There was a lot of talk, and a lot of coming and going. At the end of it all, negotiations had not advanced one centimeter.''
Argentina's foreign minister said, ''There has been no tangible progress yet.''
Secretary Haig continued meetings with Argentine officials Sunday afternoon. It was expected he would stay on beyond his scheduled April 19 departure if there were any sign of progress.
But at this writing there is precious little optimism in Buenos Aires. The issue of sovereignty over the Falklands is a clear stumbling block. The Argentines won't budge on that issue. The Falklands are theirs, they say -- not only by right of physical occupation, but by right of sovereignty.
There is some evidence that Mr. Haig is trying to separate sovereignty from all the other issues, hoping that in this way he can resolve the more soluble problems and then turn to sovereignty as the final issue.
But in private Argentine government officials say the US is not acting as an honest broker, and that it is more pro-British than pro-Argentine.
Issues of national honor and, ultimately, the future of the islands and the outspokenly pro-British 1,800 settlers on the islands are similarly involved -- and so far unresolved.
There were hints here over the weekend that the very future of General Galtieri's government may depend on the outcome of the talks. Rumors flew throughout the weekend that fellow generals were waiting like a pack of wolves for General Galtieri's hide.
The generals are said to want the dispute ended in Argentina's favor and are becoming impatient with the talks.
Meanwhile, the Argentine people -- at least those here in Buenos Aires -- watched developments with what must be characterized a bemused attitude, a bit of amused disbelief that the Falklands crisis had reached the stage it has.
While the Galtieri government continued to receive a massive outpouring of public support, both orchestrated and spontaneous, for its seizure of the British islands two weeks ago, there was at least the beginning of an attitude that maybe the generals had ''made yet another mistake,'' as an Argentine businessman suggested.
That belief was reinforced Saturday when the US mediators packed up preparatory to leaving after no progress was registered Friday. With much of Mr. Haig's staff already on board Air Force Two at Buenos Aires' Ezeiza airport, there was a switch in plans as General Galtieri called Mr. Haig back for further conversations.
General Haig then spent more than 12 hours closeted at the Casa Rosada, the Argentine White House, with General Galtieri and Foreign Minister Costa Mendez. Close to midnight Saturday night, Mr. Haig returned to his rooms at the Buenos Aires Sheraton, saying cryptically, ''We are still talking.''
US spokesmen would go no further. But it was obvious the Argentines wanted more talks. They clearly asked Mr. Haig to stay. But the Argentine position that the islands are theirs remained firm. Prospects for maneuver looked increasingly slim.
The weekend negotiations continued against the backdrop of the slow progress of British warships toward the South Atlantic and the Falklands, which the Argentines have renamed the Islas Malvinas. A clash between the Argentines and the British was still a distinct possibility.
But there was debate here on where the British ships were and whether they were moving as fast as they could.
The Argentines continued to fortify and supply the Falklands. Some 10,000 Argentine soldiers are already there, and more are arriving daily. Provisions for these soldiers are a criticial point. But Argentine quartermaster spokesmen say there are enough supplies on the islands to cope with a prolonged British blockade and siege if that should occur.
The fate of 1,800 British subjects on the islands was clearly troubling almost everyone. The Argentines in newspaper and television stories said the islanders were increasingly happy with Argentine rule and with the gentleness of the occupying troops.
Pictures of Argentine soldiers playing soccer with Falkland Island children, giving them candy, and talking with adult islanders were in all the newspapers here.
But an NBC film crew that managed to get to the islands for four hours Friday had interviews with islanders asking the British to hurry up and rescue them from Argentine rule.