For arid Niger, a large but vulnerable central African country, the future largely depends on support from neighboring Algeria and Nigeria as well as the former colonial power, France, to fend off the territorial ambitions of Libya's Muammar Qaddafi.

Despite some economic gains from export of abundant uranium, Niger remains a poor country of Sahelian scrubland and Sahara desert. It presents a classic example of how a frail African state can be at the mercy of stronger neighbors that can undermine its independence.

Niger's dependent predicament is of the sort that has enshrined Africa's guiding post-colonial principle of non-interference in internal affairs. It illustrates, in retrospect, why there was such a mixed African reaction in 1979 to Tanzania's precedent-setting intervention in Uganda to topple the universally despised dictator Idi Amin.

Many African leaders are aware that their neighbors or other external powers can bring down their governments just as easily.

Last December, Nigeriens became particularly jittery after the decisive Libyan military intervention in the civil war in Chad, Niger's similarly weak eastern neighbor. Several thousand Libyan troops remain in Chad, ostensibly to protect its transitional government from what Qaddafi says are designs on the part of the Egyptians, Sudanese and French.

Qaddafi continues to push for a controversial merger of Libya with Chad. It is open to question whether the Libyans' merger effort is popular among the majority in Chad, which like Niger is a former French colony.

"We tell France and the whole world that Chad is linked to Libya, Libya is linked to Chad, by destiny, geographically, humanly, historically, futuristically, by security and economically," Qaddafi said in a speech last month.

In what must have been a chilling comment for the anxious Nigeriens, Qaddafi also declared: "We consider [Niger] second in line after Chad."

Long a recipient of millions of dollars in economic aid from Libya's oil earnings, the Nigeriens' relations with Libya began to deteriorate rapidly last October after Qaddafi publicly accused them and the neighboring state of Mali of persecuting Touareg desert nomads.

"Libya's borders are open to the Touaregs, free sons of Arab nation, who are suffering repression and extermination in camps in Mali and Niger," Qaddafi said at the time.

Qaddafi's description of the fiercely independent Touaregs as "Arab sons" was greeted here with scorn. Touraregs have a long history of armed conflict with Arabs. The Nigeriens saw the charge as an attempt to stir up racial animosities between black southerners and the lighter-skinned desert nomads.

All of the Touraregs are Moslems, as are all but 15 percent of the 5 million Nigeriens.

In Chad's 15-year civil wary, Qaddafi backed the northern desert dwellers' insurrection against the southern-controlled government. All sides were so weakened that the Libyans were able to lead the faction of their choosing to victory. The French had withdrawn their backing for the southerners in early 1979.

Nigerien military head of state Col. Seyni Kountche said in November that Qaddafi is trying to stir up existing ethnic animosities in Niger, much as in Chad, to make way for a Libyan takeover.

Libya has also laid claim to 200 square miles of northern Niger, including some of the uranium-bearing land. Several years ago, Libya sent troops to occupy an oasis on the border despite Nigerien protests.

Thousands of Nigeriens have continued to migrate to Libya for work, however, and Libya has poured millions of dollars into Niger, sending Islamic instructors, building some 20 mosques around the country and improving health services and transport.

For several years now, Nigeriens have quietly complained that Qaddafi have shanghaied their job-seeking migrants into his Islamic Legion or the regular Libyan Army. In his recent speech, Qaddafi said it was the Libyans' "right to mobilize" Nigeriens and other African migrants into their armed forces once these people entered Libya.

Senegal, Gambia and Ghana have broken ties with Libya over the last year, charging that their nationals were recruited and kidnaped into Libya's Army for forced military training. Officials also charged that the trainees were to be sent back to overthrow their governments. The Nigeriens have now made the same accusation.

Qaddafi's goal seems to be a pan-Islamic republic under Libyan dominance, stretching across western and northern Africa. His critics charge that his method is to destablize the fragile governments in West Africa.

"The behavior of Qaddafi towards Niger is not behavior towards only one country but is part of a global strategy for West Africa," said Kountche in an interview. "The case of Chad is not only a tragedy, but a humiliation and really a shame for any human being who is considered to be civilized and free."

Kountche broke diplomatic relations with Libya, as did Mali, after the January announcement from Tripoli of the Libya-Chad merger and an almost simultaneous announcement that Libya was changing its embassy in Niamey into a "People's Bureau." Sales of uranium to Libya, long one of Niger's reliable customers, were also ended.

In his speech, Qaddafi raised the specter of cutting off aid to Niger and for the first time broached the subject of the "thousands of Nigerien workers who earn a living from working in Libya" -- leaving unsaid what he would do with them.

In terms of numbers and equipment, Niger's Army of 2,500 soldiers would not be a match for Libya's heavily equipped Army of 35,000, but the devoutly Moslem Kountche vowed a fight if Qaddafi sends in troops. "I would like to say that our people do not only need arms to fight but their faith as well."

Since Niger's break in relations with Libya, France reportedly has guaranteed Kountche direct military assistance should Libya attack. France buys half of Niger's 4,000-ton annual uranium production.

For reasons of regional stability and concerns about Libyan-inspired upheavals spilling into their countries, Algeria and Nigeria reportedly also have assured the Nigeriens of military assistance.

Niger and Nigeria, black Africa's most powerful state, are thinking about a mutual defense pact with Cameroon, Kountche said. All three countries are contiguous with Chad.