Buenos Aires — Officially, Argentina is under a state of siege. But in practice it is experiencing the first perceptible, if still faint, winds of change.
The military government is allowing once-silenced members of its opposition to speak out. Criticism of the government is widely reported in the local press, and books by government opponents are sold openly on street corners.
Among the best sellers sold across the counter in this nation's sophisticated cities are numerous biographies of the late Gen. Juan Domingo Peron, the former Argentine president whose wife and successor, ''Isabelita,'' was toppled by a military coup in 1976.
But traffic police, not soldiers, patrol the streets these days. There is less fear in Argentina than in the two years surrounding the 1976 coup -- a period during which the military declared a ''holy war'' on the country's left-wing guerrilla movements.
The government of Gen. Leopoldo Gal-tieri is edging into cautious political liberalization. And the shift grips Argentina's military government in a strange paradox. Both junta opponents and entrenched military leaders are warily watching the change.
The government is drawing up a statute authorizing political parties to stage democratic, internal elections before the end of the year -- despite the stage of siege that in theory proscribes such activity.
It also has given approval to the ambitious economic policy of Roberto Alemann, an orthodox monetarist who believes in austerity and denationalization as the solution for Argentina's crippled finances.
How to reconcile the liberalizations and a new economic program -- without unleashing political and social violence similar to that which surrounded the coup in 1976 - is the major problem confronting the generals.
Argentina's opposition parties are unconvinced by President Galtieri's gradual shift to democracy.
They believe that a subtle attempt is being made to isolate the political parties and replace them with a semiofficial government party based around the present military regime -- a development similar to what occurred in Brazil in the 1960s.
A statement issued by a grouping of the five major parties, including the Peronists, said recently: ''The people demand respectufquoteHow to initiate liberalization -- without unleashing violence -- is the problem confronting the generals.
and only receive aggression. The people demand justice and get indifference. They demand freedom and have to put up with threats.''
Leaders of the five parties have opened negotiations with once-powerful unions, which the junta outlawed, in what some suggest is a summer of discontent.
Some military figures are finding fault with the junta's plans. The economic program sets the government on a collision course with entrenched military interests. Many members of the military have been deeply involved in the country's industrial development through the management of state enterprises.
Mr. Alemann had set himself the priority of fighting inflation by freezing salary increases, denationalizing the state sector, and generally opening the economy to ''free market forces.''
Denationalization plans include opening a number of state banks to private shareholding and opening the country's nascent oil industry to foreign investment.
The economic plans could produce a situation in which the military regime faces a type of revolt within its own ranks. Certainly Galtieri's recently ordered arrest of a retired admiral and former member of the junta, Emilio Massera, along with former Argentine President Gen. Carlos Ongania, kindled some lurking resentment.
The junta was unabashedly authoritarian in its early years. There was wide-scale repression, brutal political assassinations by both left and right, and dozens of kidnappings almost every day.
Human-rights sources estimate that political prisoners are being released at a rate of about 20 a month. Today there are an estimated 1,200 Argentines in jail for political reasons, compared with about 8,000 at the end of 1976. And over the last year there were just six kidnappings, only one of which resulted in death.
But there is still protest. A group of women demonstrates each week outside the presidential palace demanding that the military clarify the names and whereabouts of an estimated 65,000 Argentinians who disappeared during the mid to late '70s and are presumed dead.
President Galtieri is trying hard to present himself as a more convincing political figure than his predecessor, Gen. Roberto Viola, who was removed in December after only eight months in office.
Galtieri has consolidated his position as commander in chief by appointing allies to head the Army unit that is the traditional linchpin of coup attempts. However, there are rumblings of discontent within the military. And Galtieri will be walking a tightrope in the months to come.