It remains to be seen whether the pressure on Romania to change its mind over Afghanistan was economic or military -- or both. But there is no doubt the heat was on. And this time Romania, which often has been boldly at variance with Soviet foreign policy, backed away from its initial opposition to the Soviet invasion.
Among the likely reasons:
* Despite the rapid growth of trade and economic preferences with the West, it remains heavily dependent on the Soviet Union for such basic raw materials as iron ore and pig iron.
* Afther the interruption of substantial supplies of oil from Iran, negotiated originally with the deposed Shah, it seems to have seen no option but to turn to the Soviets to make good the gap between output from its own fields, which are running down, and its rapidly mounting needs.
The dramatic change in policy was evident after three days of intensive talks in Bucharest between Soviet Foreign Minister Andrei Gromyko and Romanian President Nicolae Ceausescu.
Quite clearly, Mr. Gromyko was visiting in his capacity as a member of the Soviet Union's tough policymaking Politburo as much as its spokesman in international affairs. The unsmiling, watchful countenances of both men at their first meeting -- as seen on television news screens -- suggested that serious business was on hand.
The resulting communique, as issued by the Romanian news agency Feb. 2, made no direct reference to Afghanistan.
But it proclaimed agreement that the "recent aggravation" of the international situation was the result of an "accumulation of unresolved world problems arising from the interference of the imperialist forces in the the internal affairs of other states and the use of force in international relations."
The "imperialist, reactionary forces," the communique continued, "use this in order to increase military budgets, speed up long-term arms programs, infringe . . . states' independence and sovereignty, a fact that seriously heightens the danger of war."
Romania's move is surprising. But the delicacy of its position had been emphasized by its behavior at the United Nations debate, which voted overwhelmingly to demand the immediate withdrawal of Soviet troops.
Romania was one of 12 "absentees." Afterward, it explained why in terms that nevertheless demonstrated its own disapproval of interference of any kind in another state's affairs.
In the past it had often condemned both superpowers and their "bloc policies" and demanded an end to both military alliance, NATO and the Warsaw Pact. Frequently, however, it was plainly more critical of Russia than of the West.
It has often been at odds with its allies over internal Warsaw Pact matters. In 1958 it secured the withdrawal of soviet troops based in Romania since World War II. For many years it refused to allow Russian or other pact forces to conduct exercises on Romanian soil.
Only in recent years has it modified this stand to permit token staff and communications tryouts in Romania and to take part itself. It refused to participate in the 1968 Soviet-led invasion of Czechoslovakia, unequivocally condemned it, and has not changed its position since.
What then caused Mr. Ceausescu to back away from a similar (though less unequivocal) stand on Afghanistan and to join Russia in blaming the present crisis on the United States and the West and agreeing that the "firmest action" was needed to keep the crisis from worsening?
One possible explanation is the different circumstances. Czechoslovakia was an essential, central part of Russia's postwar security system between itself and the old aggressor, Germany.
This was, in effect, recognized by the West, and to that extent the Soviets could "justify" the move without significant risk of more than verbal conflict with the West.
In Soviet reckoning, Afghanistan is in a quite different category, in a part of the world where superpower rivalry is at its most intense and where Mr. Brezhnev claimed Jan. 13 to see the "buildup" by the "imperialist powers" of a "serious seat of danger" to Russia's security on its southern border.