In recent weeks the government of Chad has come to see that it faces two challenges: 1. In the north, its troops must hold a line against the advance of the Libyan-backed rebels of former Chad President Goukhouni Woddei.
2. In the south, it must try to quell another rising dissident movement. Toward this end, President Hissein Habre reportedly is diverting some of his troops from the northern zone to the south of the country.
The southern dissident campaign is ''more than a nuisance but less than a threat,'' says a Western diplomat in N'Djamena. But it is apparently serious enough that the Chadian leadership is redeploying some of its troops from northern front-line positions to the south. (Earlier, President Habre had transferred most of his forces stationed in the south to the north to counter the Libyan invasion.)
The Monitor has learned from Western sources in the Chadian capital that President Habre has asked the US to spend at least part of its remaining allotment of military assistance to Chad on trucks and jeeps for use in battles against the southern dissidents.
Chad's information minister has described the southern dissidents as ''bandits'' financed by Libya who are trying to destabilize Chad. ''The violence in the south has no political character,'' Information Minister Soumalia Mahamet says.
But many observers take a different view.
''Some of the robberies and violence . . . are being carried out by bandits, '' a Western source in N'Djamena says. He agrees that Libya has trained and financed some of the southerners. But he adds, ''This cannot hide the fact that most of the fighting in the south is being carried out by highly organized and well-armed groups whose motives are clearly political and who have nothing in common with the Libyans except their antipathy to President Habre.''
Most of these dissidents, sources say, are former members of southern leader Wadal Abdelkader Kamougue's forces - who were driven out of the country when Habre's forces swept into the south in September 1982. Their goal, sources say, is to create an independent southern state or at least a semi-autonomous southern region.
They seek a break with Habre in part because government troops reportedly have killed and harassed southerners. But north-south tensions have plagued the country since independence in 1960. And fighting between ethnic groups in the two regions has been one of the reasons for Chad's instability.
''When (Habre's) FANT forces first moved into the south in September 1982, it gave them a chance to get even for the southern-dominated national army's humiliating occupation of the north in the 1960s and early 1970s,'' says a Western source who has lived in the south. ''When the FANT forces began to commit atrocities, it was only natural that the southerners . . . began to fight back.''
According to African and Western diplomats in N'Djamena, the southern dissidents are striking mainly against government troop positions and Chadian government installations in the south.
Western sources indicate that most of the fighting between the southern dissidents and FANT troops is occurring within a 50-mile radius of the southern town of Moundou. In this area, especially near the hardest hit villages of Djouma, Kelo, Bere, Dafra, and Doiti, all missionaries have been evacuated and commercial and government vehicles cannot travel without an armed escort.
Like most other African nations, Chad is an artificial entity whose frontiers were created by the European colonial powers in 1885 at a conference in Berlin.
In Chad, this process of state creation produced a country in which ''disperate and often hostile ethnic groups were thrown together into one state even though the different groups had not developed a national consciousness,'' a Western official says. ''The result was built-in political instability as competing ethnic groups fought over limited resources.''
While the inhabitants of northern Chad are mostly nomadic or seminomadic Arab and Afro-Arab ethnic groups who are Muslim and look to North Africa and the Middle East for spiritual identification, southern Chadians are mainly black Nilotic tribesmen who practice Christian or animist religions and are farmers. The differences between the groups were exacerbated during more than 50 years of French colonial rule.
While the French ignored northern Chad, finding little to exploit in its harsh desert environment, the south was developed with large-scale cotton farms. Missionaries established churches and schools in the south.
The result of this uneven development was that at independence in 1960, southerners dominated all the top government positions.
Northerners created the Chad National Liberation Front (Frolinat) and began armed struggle.
By 1978, northern guerrilla leader Hissein Habre had an army strong enough to challenge Felix Malloum's government. It forced Malloum to accept a power-sharing arrangement, which gave the northerners a stake in the central government for the first time.
But the Malloum-Habre coalition broke down only six months later and the country was plunged into a bloody civil war.
Since that time, regional mistrust and hatred have poisoned almost every aspect of the nation's social, political, and economic life. And it is plaguing President Habre, who despite his northern roots has made some attempts at national reconciliation.
Habre has placed some southerners in his Cabinet. He also won some goodwill among southerners with his efforts to pay the salaries of civil servants, who for years could not count on getting paid.
But most southerners are not impressed by President Habre's efforts to mollify north-south hostilities. As a southerner from Moundou explains, ''How can you respect or trust a man (Habre) who has spent all of his adult life fighting against your brothers?''
President Francois Mitterrand's recent call for a federal solution to Chad's problems - although rejected by President Habre as a ''recipe for the permanent partition of Chad'' - has further emboldened southern dissidents, who now believe the French will support their demands for a semiautonomous southern region.