Tunisians talk about Muammar Qaddafi the way a suburban homeowner might talk about the man next door on parole for arson. There is a bit of fear in their voices. They are trying to think of what to do about it. "But in the end, you can't choose your neighbors," one senior official said, with a shrug.

Yet Qaddafi's is not the only problematic presence in the North African neighborhood, where everyone talks about unity but none of the five nations is ever quite comfortable with the other four.

Border disputes, ideology and disparate wealth are forever dividing them unpredictably into uneasy alliances and axes -- and Qaddafi, however unneighborly he may be, is always included on one side or the other.

In recent years, a 1983 friendship treaty between Tunisia and Algeria and a 1984 pact of union between Morocco and Libya have split the region into hostile camps.

Now Libya's expulsion of almost 30,000 Tunisian workers and their families since Aug. 5 has provoked more anger than the western Arab world has seen in years.

Tunisia, smallest of the states and with a powerful sense of vulnerability, promotes the idea that Qaddafi is capable of anything. With him around, "it is practically the law of the jungle on the international level," a Tunisian official said.

Tunisia's answer to the threat has been to call on its friends to show support. The United States has sent some carefully calibrated signals trying to show just where it stands.

Earlier this month the U.S. chief of naval operations, Adm. James Watkins, went to Tunisia in a visit that both American and Tunisian officials viewed as a useful warning to Qaddafi that Washington strongly supports the government of Tunisian President Habib Bourguiba in the current crisis.

Algerian President Chadli Bendjedid paid a surprise visit here, affirming Algeria's solidarity with Tunisia and leaving the door open to Algerian military involvement on Tunisia's side if Tunisia is attacked by Libya.

Tunisia's Army has about 30,000 men, compared to Libya's 73,000. Tunisia's major cities are within easy reach of the powerful Libyan Air Force and Tunis is only a seven-hour drive from the frontier. But Algeria has an Army almost twice the size of Libya's.

Algeria would support Tunisia "in all circumstances," Bendjedid was quoted as saying on his visit.

French Ambassador Eric Rouleau also has made known his country's support for Tunisia.

"Even Qaddafi is not going to be indifferent to the interest of the U.S., France and Algeria in Tunisia's territorial integrity," one western observer said. "And this reduces the chance of his doing us all the favor of presenting a clearcut casus belli."

But there is concern among diplomats here that if fighting did start, the complex web of connections and enmities among the countries of the region could cause it to spread very quickly.

The situation has been complicated by the signing last year of the union between Libya's revolutionary regime and the conservative kingdom of Morocco, which many observers see primarily as a united front against Algeria. Senior Moroccan government officials often describe the union privately as a "marriage of convenience."

For a decade, Algiers has been fighting indirectly against Morocco's King Hassan II by supporting the Polisario guerrilla movement challenging him for control of the former Spanish Sahara.

Libya also supported the Polisario until Hassan made the surprise move last year of proposing the union. Both countries had come to feel increasingly isolated internationally after bids for support from the Organization of African Unity failed.

Qaddafi also seemed to resent the 1983 Algerian-Tunisian treaty of "fraternity and concord," in which he and Hassan were not included.

The Libyan-Moroccan union was signed on Aug. 13, 1984, much to Washington's consternation, since the United States traditionally has supported Morocco almost as much as it has reviled Qaddafi's Libya.

But the cessation of Libyan military support to the Polisario over the past year has been a major advantage in Morocco's efforts to crush the Polisario.

Other attempts to implement the union have had less success. Yet the pact has taken on a life of its own. A bureaucracy has been set up.

Tunisia appears to have been caught in the squeeze.

"We did not consider that the Moroccan-Libyan pact was an axis formed against us," Tunisian Foreign Minister Caid Essebsi said. "But the new Libyan action" -- the expulsion of Tunisian workers -- "does give us the impression that the Maghreb is split in half."

Egypt, the fifth country in Arab north Africa -- a natural ally of Tunisia and a fellow victim of the Libyan expulsions -- remains on the sidelines because it made peace with Israel.

For the moment, Tunisia's loss is Morocco's gain. As Libya is throwing out Tunisian and Egyptian laborers, it is reported by western journalists in Tripoli to have been expanding its employment of Moroccans.