The Reagan administration is in a quandary about how best to restrain or contain Libyan leader Muammar al- Qaddafi. Colonel Qaddafi has put the cat among the pigeons by taking over most of Libya's neighbor, Chad. This he has done ostensibly with a view to a political merger of the two countries concurred in by Chad's legitimate President Goukhouni Woddei.
Compounding the challenge this presents is the developing relationship between Colonel Qaddafi and the Soviet Union. In Libya are estimated to be 5, 000 Soviet-bloc personnel of one kind or another and an arsenal of Soviet weapons worth $12 billion.
Despite the outrage this combination has provoked in the United States, in France, and in African countries bordering Libya and Chad, Colonel Qaddafi has leverage which he skillfully uses against those who want to force a Libyan withdrawal from Chad. For example:
* He can argue that the Libyan presence in Chad is legitimate, since he was invited in by President Goukhouni under a treaty negotiated last year between the two governments. (President Goukhouni needed Libyan help to defeat the insurgency of his defense minister, Hissein Habre.)
* Libya appears to be the only country able and willing to put up the vast amount of money needed to help get Chad -- one of the world's poorest and least developed countries -- onto its feet after 15 years of civil war.
* Libya is the source of some of the most attractive lowsulfur oil on the market. It is the third-largest foreign supplier of oil to the US. Both West Germany and Italy buy considerable quantities of Libyan oil, too, and France repeatedly has shown an interest in increasing its share of Libyan oil exports. Colonel Qaddafi has developed considerable skill in manipulating this dependence to his advantage.
Yet there are disturbing questions needing definitive answers. Among them:
* Is Colonel Qaddafi a "surrogate" of the Soviet Union, in the full sense of the word, as President Reagan described him in a television interview March 3? In other words, is the Libyan leader the same kind of proxy for Moscow as Cuban leader Fidel Castro?
* Would be allow the Soviets to use Libya, in time of superpower confrontation, as a base from which to threaten the NATO position in the Mediterranean and southern Europe?
* Will he use his partial occupation of Libya's southern neighbor, Chad, as a base to establish an Islamic entity under his control along most of the southern rim of the Sahara? What exactly did he mean when he said in a speech March 2 that Niger was "second in line after Chad"?
* Does he intend to use his new position in Chad to outflank both Egypt and Sudan, or at least to threaten through Sudan the waters of the Nile, without which Egypt cannot live?
Egypt obviously thinks this latter is a possibility. Only this week Egyptian Foreign Minister Kamal Hassan Ali confirmed that Egypt was giving support to the defeated anti- Libyan dissident group in Chad led by former Defense Minister Habre. After losing to President Goukhouni and the Libyans, Mr. Habre fled to Abeche in eastern Chad. After the Libyans drove him from there, he took refuge in Sudan.
He is probably the best educated (in the Western sense) of the northern Chadians active in the present struggle, but that is in some ways a liability in Muslim Saharan Africa. Consequently, the Egyptians may be backing a weak reed.
In any case, Egypt is less a key outside protagonist in the Chad drama than are Nigeria and France.
France had troops of its own in Chad until last year and was for long the country's protector and patron. It still has troops in the former French African territories of the Central African Republic (which abuts Chad), the Ivory Coast, Senegal, Gabon, and Djibouti. The French government has said since the Libyan thrust into Chad that it would send military aid to other French-speaking African states, provided their governments requested it.
Niger, perceived by many to be the most immediately threatened of these states, has pointedly refrained from making such a request -- presumably to avoid provoking Colonel Qaddafi, who was mocking of the Niger government in his March 2 speech. Niger has important uranium deposits near Arlit. Some observers think the Libyan leader covets this uranium to facilitate the development of the Islamic nuclear bomb with which he yearns to confront the world.
But for the moment, France is partly immobilized in the foreign policy field by the campaign for next month's presidential election campaign. That leaves Nigeria, in whose court the ball now is.
Nigeria is the giant of black Africa, has a sort common border with Chad, and is deeply concerned about the destabilizing effect of Colonel Qaddafi's revolutionary Islam in the Muslim sub-Saharan belt of Africa. The northern part of Nigeria lies wihtin that belt.
Nigeria is not working unilaterally to counter Colonel Qaddafi's thrust southward. Instead it is using its considerable clout within the Organization of African Unity (OAU) to mount an initiative to try to get Libyan troops out of Chad.
An OAU ad hoc committee has come up with a plan for an OAU peacekeeping force to replace Libyan troops in Chad, if the Libyans can be persuaded to withdraw. The peacekeeping force would be provided by Nigeria, Cameroon, and Algeria. Willingness of the latter to contribute is significant, for it suggests a growing concern on the part of Algerian President Chadli Benjedid about Colonel Qaddafi's intentions.
It remains to be seen whether the OAU can generate enough pressure to get Colonel Qaddafi to withdraw from Chad. Some observers doubt it. They doubt too whether the OAU will be able to come up with the money needed to replace that already promised Chad by Colonel Qaddafi, running at tens of millions of dollars.
As for the Libyan occupation of Chad, it is not complete. The estimated 7, 000 Libyans in the country have not moved south of the Ndjamena-Abeche road. The area south of that road is the homeland of Chad's southerns (50 percent of the population) and is virtually the only food-producing part of Chad. The southerners are more anti-Libyan than northerners -- largely because, unlike northerners, they do not share with Libyans the common religion of Islam.
President Goukhouni's vice-president, Col. Wadal Abdelkadar Kamougue, is a southerner and has been noticeably cool toward the Libyan connection. He has remained in the south since the Libyans reached Ndjamena. There is speculation that he may be biding his time and assessing whether to promote the eventual secession of the south f rom the north.