The inter-African peacekeeping force in Chad has managed for the moment to block resumption of civil war in that troubled, largely desert land.
But it is another question whether the force has sufficient resources and outside support to hold the line long enough for a negotiated, peaceful compromise in the stalled internal power struggle in Chad.
What happens in Chad is important far beyond its borders because of the threat of renewed Libyan intervention in its affairs. Libyan leader Muammar Qaddafi, almost public enemy No. 1 to the Reagan administration in Washington, is a potential ally of the Soviet Union.
The two main contestants for power in Chad are the President of the interim government, Goukhouni Woddei, and Hissein Habre, Woddei's former defense minister. Late in 1980, Woddei called in Libyan troops to help him defeat Habre. This done, Habre's forces withdrew to the Sudan border in the east.
In October last year, President Woddei (encouraged by France, the former colonial power in Chad) asked the Libyans to withdraw. Colonel Qaddafi promptly complied, getting his troops out before the Organization of African Unity (OAU) could get a peacekeeping force into Chad to take the Libyans' place.
In the resulting vacuum, Mr. Habre has managed to sweep back westward with his men. They have captured Ati, and some reports put them in possession of Faya-Largeau, two centers from which they threaten Mr. Woddei's base in the Chad capital, N'djamena.
The OAU force, still not fully deployed in Chad, has hurried units to the Ati and Faya-Largeau areas to serve as token roadblocks against further advances by Habre toward N'djamena.
This in itself is something of an achievement after weeks of debate about what the role of the OAU force should be. In effect, President Woddei wanted the force to fight Habre for him, since Chad's central Army is itself such a weak reed. The African contributors to the force have from the outset been reluctant to get directly involved in the domestic politics of a fellow African state.
But against Woddei's achievement must be set these reservations:
* Of the six countries originally intended to provide units for the OAU force , only three -- Nigeria, Zaire, and Senegal -- have come through. The force is still at only about half its planned strength. (The defaulters are Benin, Guinea , and Togo.)
* The OAU has been unable to provide adequate funding for the force, despite an advance from the US of $6 million apiece to the Nigerian and Zairean contingents, and France's pledge of outright support of the Senegalese contingent for five months.
* A lingering ambiguity about the exact role of the OAU force, particularly if it finds itself physically caught in actual hostilities between the Woddei and Habre forces.
* A parallel lingering ambiguity about the exact roles in the struggle of the US and France. Both powers say they back the OAU and France's pledge to further internal reconciliation in Chad.
Between Woddei and Habre, the President is seen as ''softer'' toward Libya than his challenger. Both the US and France want to keep Libya out of Chad. To that end, the French -- less intransigent toward Libya on broad issues than is the US -- is working with or through Woddei. As for the US, the suspicion persists in some quarters that Washington would not be averse to seeing the tougher and more vigorously anti-Libyan Habre come out on top in any ''internal'' solution to Chad's woes.
Whether or not that suspicion is justified, Woddei has grounds for believing that, left to face Habre on his own, Habre might well win the power struggle. Most outsiders agree that the latter's ''armed forces of the north'' would probably outfight Woddei's almost phantom Chad national Army.
Indicative of the concern that the whole peacekeeping effort could still unravel are:
* French President Francois Mitterrand's sending of one of his top Africa advisers, Guy Penne, to Nigeria last week for consultations. (A Nigerian, Gen. Geoffrey Ejiga commands the OAU force, and Nigerians supply the single biggest national contingent to it.)
* The convening of an emergency meeting Feb. 1 and 2 of the OAU standing committee on Chad,called by OAU chairman Daniel arap Moi, President of Kenya. The Nigerians, in particular, have been critical of Mr. arap Moi on the grounds that he has not been supportive enough of the Chad effort, after failing to get a Kenyan appointed OAU force commander.