British gains may speed a settlement

With the British Union Jack again flying over the Falkland Islands, even if only at beachheads, the Anglo-Argentine conflict over the islands enters a new and critical phase.

It offers fresh opportunity for a negotiated settlement of the seven-week-old dispute. But it is also a moment fraught with large uncertainties about further military moves by Argentina and Britain -- and the danger that the fighting could escalate.

Neither the Argentine military junta, headed by Lt. Gen. Leopoldo Fortunato Galtieri, nor Prime Minister Margaret Thatcher's government in Britain can survive a defeat on the Falklands battlefield -- much less a negotiated settlement perceived at home as a defeat. In the eyes of many observers, this unfortunately argues for more fighting.

At this moment, the threat of such defeat is most pressing on General Galtieri. He conceded late May 22 that ''the enemy has successfully obtained a foothold in the zone of San Carlos.'' He cannot, however, go on making such concessions if his government is to survive.

But as the British continue to expand their Falklands toehold from its initial beachhead at Port San Carlos on East Falkland, the apparent superiority of British muscle and tactics could prove increasingly embarrassing for the generals in Buenos Aires, no matter how much damage is done at the same time to British forces.

Although Argentine communiques have yet to fully reflect the extent of the British landings with an estimated 5,000 troops, the generals and admirals in Buenos Aires are acutely aware of the military dangers they face.

British military muscle and the British penchant for surprise have combined to quickly put Britain into a favorable tactical position on the Falklands. Superiority in numbers still rests with Argentina, but ultimate superiority may come down more on the side of the British with their tactical advantages. The downing of 21 Argentine airplanes and helicopters in the British landings, for example, was a high toll to pay for the one branch of the Argentine military that all along has been regarded as a match for the British.

The Argentine military in Buenos Aires may feel the need to strike out anew in some dramatic, but possibly dangerous fashion to counter and minimize the British advantage. The most obvious possibilities center on the dispatch of two sophisticated submarines, the remaining pride of the Argentine Navy, and/or an aerial flotilla of advanced Argentine Mirage fighter jets toward the British armada in Falkland waters in an effort to inflict major damage to the fleet.

But that in turn, of course, would likely prompt a British response which, in the extreme, might include raids on Argentine mainland naval and aerial bases such as those at Bahia Blanca, Comodoro Rivadavia, Rio Gallegos, and Trelew.

Even without some new Argentine move, the British are certain to expand their military operations in the Falklands -- unless there is an early move back to the negotiating table. Likely British military moves include the widening of their beachheads on the Falklands, the establishing of new ones, and continuing attacks on the key Argentine bases at Port Stanley, the Falklands capital, and Port Darwin, as well as the airports at both sites.

It is not overlooked in Buenos Aires that the requistioned cruise liner QE II is now approaching Falkland waters with its large complement of new British troops including the much-publicized Nepalese Gurkhas.

All this combines to put new pressure on General Galtieri to save face by finding a way to end the fighting without having it appear as defeat.

The push for a settlement, moreover, stems from the recognition by both Buenos Aires and London that more fighting over the islands can only lead to losses in human lives likely to dwarf those already suffered by both nations.

Both sides recognize that now may be a propitious moment for a settlement. ''The hour is late,'' an Argentine Foreign Ministry official commented May 21 as the British were landing on the Falklands. ''A return to negotiations is the only avenue to prevent more bloodshed.''

Whether this counsel will be heeded by Argentina's generals remains to be seen.

Argentine Foreign Minister Nicanor Costa Mendez, for his part, is again in New York to plead the Argentine case to the United Nations Security Council. His presence at the UN could lead to fresh talks aimed at winning a cease-fire in the conflict. The Argentine will certainly confer with UN Secretary General Javier Perez de Cuellar.

It was the failure this past week of the latter's valiant two-week effort to bring the two sides together that signaled the go-ahead for Britain's landing on the Falklands Friday.

Now with the British holding their ever-widening perches on the Falklands -- one main site at Port San Carlos and several other smaller, but important bridgeheads elsewhere -- it is possible that the scene will shift back to New York and to UN-sponsored negotiations. Britain has, after all, restored a bit of British sovereignty to the islands, reversing its ejection from the islands last April 2 when the Argentines invaded. The sides are more even diplomatically.

For the moment, British Foreign Secretary Francis Pym indicates he hasn't any plans to go to New York for peace talks, but British spokesmen say Mrs. Thatcher's government remains ready for new negotiations if they hold promise of any success.

But Britain clearly is not prepared to lose any of the advantage that its return to the Falklands gives it. If there is an eventual move to the negotiating table, Britain will be certain to make the most of its advantage provided by the expanding beachhead.