A treaty of ''nonaggression and good neighborliness'' with Mozambique. A ''joint monitoring'' agreement with Angola. Cuban-Angolan discussions about troop withdrawals. An offer to turn over administration of Namibia to five Western countries. Release of the long-imprisoned Namibian leader Herman Toivo ja Toivo. These events in 1984 constitute a rapid succession of fissures in the long-frozen southern African political glacier.
Do these unprecedented moves by the South African government in Pretoria and its Marxist-Leninist neighbors portend a breakup of the regional ice jam - a genuine political springtime for one of the world's most troubled spots.
Or is this just another false end of winter, likely to freeze again when it comes to the underlying issues of independence for Namibia and some form of civil rights for South Africa's 5-to-1 black majority?
As the world chancelleries ponder these questions of importance to international peace and security, some oblique illumination might be gleaned from impressions, deliberately subjective, gained recently during a first visit to the Republic of South Africa.
Johannesburg is cosmopolitan, Western, urban-upscale. A mile-high Toronto or Sydney, a Rome of hills crowded with high-rise apartment buildings. On Saturday night the gaily lit side streets with boutiques and unexpectedly nonpuritanical amusements could be in San Francisco.
The crowds are white, black, and soon-to-be semi-enfranchised Coloreds and Asians. Sunday the streets are empty of blacks, who are supposed to live elsewhere - perhaps Soweto - their families even further away in any of 10 tribal ''homelands'' to which the government has assigned them citizenship.
But here and there an illegal squatter's little aerie perches behind a fenced-over storefront, near a dazzling new glass building faceted like - what else? - a diamond. The hotels and universities are now said to be ''open.'' But somehow black faces at universities seem few and far between.
The world-class hotel restaurant is one place blacks appear in abundance, as waiters, busboys, even captains (but not maitre d's or sommeliers). Their manner conveys a subservience reminiscent of ancien regime Africa (or wartime Washington, D.C.). The smiles, however, are genuine. One senses that a less gentle and forbearing people would have overturned the racial status quo by now.
White clients seem startled when sleekly appareled Indians are ushered to the next table. A black attendant is publicly vilified by his white supervisor in a special tone of voice used in European colonial days (and also used by Americans seduced by that racial environment). A black foreign guest sits in lonely splendor at breakfast in the morning.
Cape Town: a setting of breathtaking beauty, with towering mountain walls of sheer granite framing blue water. Semitropical palms and flowering shrubs set off buildings, streets, mountain drives, and luxurious suburban homes in harmonious proportion. All in all, a city of phenomenal attractiveness, built in the 17th century by Dutch pioneers and fleeing Huguenots, later semi-dominated by the English.
On the fringe of Cape Town is a half square mile of bulldozed red earth punctuated by one small mosque and two lonely churches. This is District Six, whose Colored residents were evicted in 1966. It is still barren, the result of the Coloreds' quiet determination not to allow white gentrification on the ruins of their former homes.
But in general, the humiliating ''petty apartheid'' is much reduced in Cape Town. Gone are the signs segregating restrooms and other public facilities. Crowds mix in the shops, eating places, streets. Blacks attend the conferences, dinners, and garden parties. But they are black ambassadors or important officials and experts from the likes of Namibia or Transkei or Lesotha or Zimbabwe, and their inner tension is subtle but palpable.
Perhaps because Cape Town is the only city in which black workers are in a minority, the City Council is permissive. But the beaches are run by the provincial government and stay segregated.
Beyond the city, beyond the University of Cape Town campus perched like a rambling palace along the dramatic lower escarpment of Table Mountain, beyond the port and the elegant suburbs, is Crossroads. The black shantytown is under government decree to evacuate even farther out from city and work so that Coloreds can move in.
People wander aimlessly across sandy, treeless wastes of Crossroads like hungry cattle. On a back street one suddenly comes on a tiny schoolhouse whose dirty cinderblock exterior is graced with brightly painted frescoes, thanks to volunteer help from white Cape Town artists.
Older parts of Crossroads are more settled, and some houses along the unpaved roads boast cars in front and TV antennas on top. Some families classified as Colored, who enjoy labor preference in Cape Province, live in almost middle-class townships.
On the bare earth alongside the main highway, a lively soccer game is going on. The action is impressive enough to suggest the presence here of a younger brother or cousin of some of the talented black professional players who have succeeded in breaching the once-sacred sports color line.
But the wasteland of Crossroads, with its tin and cardboard shanties and its fields of blowing sand, is what stays in the mind's eye.
It is not that the poverty is so abject - though it is. One has seen worse on the streets of Calcutta and in the barrios of Caracas. It is that these souls jammed in their shantytowns are suddenly, arbitrarily ordered to move away, even far away, without having any voice in the matter.
In Calcutta and Caracas, in the unlikely event the poor make some money or get lucky enough, they can move into a house, into the city, or to a suburb. If they get together they can try to vote the government out of office. And, if social pressures do not make it too costly, they can marry anyone and live where they choose, without going to prison.
But in South Africa the black majority has no voice and few rights, in the sense that whites possess these things. Blacks have rights only in the ersatz ''homelands'' created by the white-minority government. These ten homelands are fragmented areas that usually consist of arid soil hundreds of miles from where their black ''residents'' work and live.
Blacks can put citizenship to practice in the homelands. But they may not move to the cities to live as families because of the nation's laws restricting where blacks may live and move.
And what of the cracks in the political ice jam? There was near-unanimity among my respondents regarding three propositions:
l. Because of the devastating African drought, economic failures of the Soviet-linked regimes in Mozambique and Angola, and South Africa's tough military pressures on its neighbors, movement on the diplomatic front is real. It could - just could - end in long-overdue independence for Namibia (whose byproduct could be a rare Reagan diplomatic triumph). But most experts are doubtful that the Namibian game will play out, even now.
2. The ruling Nationalist Party, those questioned say, has become more ''centrist,'' with its extreme right wing shown by the 1982 vote on constitutional reform to be ''impotent.'' As a ''new era of realism'' supplants ''total onslaught'' in the government's vocabulary, the leadership has a green light to pursue peace in the neighborhood, whether under UN resolution 435 or otherwise. One crucial factor is economic.
An impeccably establishment businessman who ''loves his country'' says he is one of a growing number to whom the costs of punitive military operations in the north have become ''excessive.'' But the decisive element, if it becomes widespread, could be the demoralization he reports among his friends, parents, and sons, stemming from the youths' hazardous and controversial military service ''on the border.'' When he added, ''like you Americans in Vietnam,'' one began to believe.
3. The evolving political and economic dynamic within South Africa implies a free hand for ''reform'' at home. This would presumably entail in time some form of limited representation for blacks, along the lines of the constitutional referendum that approved the establishment of two new ''separate but equal'' parliamentary chambers for Asians and Coloreds.
The United Democratic Front - a new multiracial coalition of ''progressive democrats'' - opposes the constitutional reforms as a sham in which minorities are being ''co-opted'' to the apartheid system. Some of its members claim that the ''inevitable explosion'' is being inadvertently accelerated by Pretoria - as , in its ''guilt,'' it trains ''future revolutionaries.''
But some of those same activists are privately doubtful that there can be universal suffrage any time soon. According to the more mainstream white view, particularly among English-speakers and supporters of the small anti-apartheid Progressive Federal Party, the internal problem is solvable - ''given time.''
An American is sobered by on-the-spot observation and inquiry. Some potent forces for change are in motion in South Africa. But no one of any political persuasion with whom I talked could say how, at this point in history, genuine political democracy might actually work in the South Africa of the real - as contrasted with the rhetorical - world.
Yet modest steps to bring nonwhites into the political process must lead in time to bolder measures. History is normally irreversible, and doctrines of liberty and equality are at least as catching as their opposites.
Peter Kroptokin wrote that ''the hopeless don't revolt.'' But with hope, the race may well have started between evolutionary reform and something far less desirable for both black and white Africans.