Buenos Aires — Having seized the Falklands, Argentina is a little like a man who has enjoyed a superb dinner--only to have its aftertaste spoiled by the size of the bill.
As the size of their Falklands bill grows, many Argentines are beginning to fear that their country may be going down what one high government official here calls ''a street without an exit.''
They also recognize that the cost of occupying the islands, both in pesos and in national unity, could prove much greater than whatever gain their national honor could derive from the April 2 seizure.
It wasn't supposed to be this way. After all, the occupation of the Falklands was seen here as a righteous cause, as a long overdue step to end British rule. Almost everyone was expected to applaud--and those who didn't were meant merely to limit their protest to scolding telegrams.
But instead of sending mere words of protest the British dispatched a mighty naval and air armada, which seems to grow in size daily. Similarly, military assessments of this country's ability to fend the British off are becoming less confident.
Argentines now know that Margaret Thatcher and indeed British resolve in general are made of sterner stuff than they earlier thought.
But what to do about it?
That question convulses the Argentine nation. It particulary worries the Argentine military government, headed by Lt. Gen. Leopoldo Fortunato Galtieri, which launched the Falklands invasion.
Time seemed to be running out on the diplomatic front with Secretary of State Alexander M. Haig's return to Washington from Argentina April 19. The military's realization that diplomacy is at least temporarily stalled may explain Argentina's hasty decision soon after Mr. Haig's departure to invoke the Rio de Janeiro treaty of mutual assistance.
The military obviously hopes that this eleventh-hour effort with the British armada approaching will win fellow Latin American sympathy - and perhaps even active assistance. At a minimum, the Argentine generals seemed to be banking on the appeal to provide the way out of the corner into which they have painted themselves.
But there is little expectation here that the Rio treaty, or anything else so far attempted or thought of, can pull Argentina out of its dilemma.
Few Latin American nations are excited about the prospect of supporting Argentina in its current travail. Many worry privately that the Argentine seizure of the Falklands may have opened a can of worms that could affect countless other border disputes throughout Latin America.
And the government here is clearly aware that it has opened up its own can of worms. It is not a comfortable position for the Argentine military, which has held power since 1975.
The Argentine economy is in bad shape and the cost of occupying and defending the Falkland Islands is adding to the strain. It is unclear what the occupation is actually costing--but many estimates put it at more than $1 million a day.
Inflation already was running at a high of 140 percent a year. Some estimates now suggest that the Falkland dispute will push the inflation rate to 180 or even 200 percent a year.
One can see the impact of inflation in the restaurants that dot this city. In normal times they are full, even overflowing. But now many are empty, some have closed, and most are feeling the pinch of few customers.
This economic situation is expected to worsen. Some observers here say that it could lead to growing public protest over the government's economic policies. Such protests were beginning prior to the Falklands invasion, but the government's action in taking the islands sidetracked the protest.
Newspapers suddenly were full of stories about the massive outpouring of public support for the military government, about young men volunteering for the services, and about the contributions Argentines were willing to make to the cause of retaining the islands.
But now, the talk in the cafes, on street corners, in taxicabs, on buses and trains, and, in short, just about everywhere in Buenos Aires is much less enthusiastic. Indeed, it reflects sober concern that ''the government and the people of Argentina may have bitten off more than they can chew,'' in the words of one longtime politician here.
More and more, one hears comments about the Falklands occupation being a ''mistake,'' an ''unfortunate decision,'' and similar words. Even some military officers also are beginning to show signs of concern. But this military concern is centered mostly on what Britain plans to do.
There is now little doubt here that British naval power will soon make things uncomfortable for Argentina and that the British intend to do all they can to get the Falklands back, along with their South Georgia and South Sandwich dependencies.
Moreover, the military is now aware that British naval, air, and land power was initially underestimated. The Argentines have been told by Secretary Haig, Gen. Vernon Walters, and others that British strength already is formidable - and increasing. Argentina, it is argued, would likely do poorly in any encounter with the British.
Ironically, this information on British military strength and estimates of the British ability to fight a war in the South Atlantic were given Argentina after the military here protested US military advice being given the British. The Argentines noted that Britain had been given information from US satellites concerning Argentine troop maneuvers. As a fellow ally of the US, the Argentines asked in effect why they could not have similar information on the British. The US complied--and, according to military observers here, the Argentines did not like what they heard.