Today, the Mafia is an endangered species, beleaguered by incompetent leadership, betrayals and generational changes that produced violent and unreliable leaders and recruits.

A 20-year assault against entrenched organized groups, each known as a family or by the Sicilian word borgata, blossomed into the most successful law-enforcement campaign of the last century. Almost every mob hierarchy in the country that flourished in the 1980s and 1990s has been mauled by convictions and defections. Compare these results with the endless but largely futile wars against narcotics trafficking in the US.

But paradoxically the government's successes against the mob could lead to a Mafia revival and to environmental hazards.

Despite its current problems, the Mafia may have unexpected allies for a resurgence -- the Federal Bureau of Investigation, the Justice Department and local police agencies. As priorities in combating significant crimes shift, law enforcement zeal for undermining the Mafia is decreasing. In recent years, the FBI has cut the special units assigned to mob investigations and experienced federal and state investigators and prosecutors have not been replaced.

Given time to recuperate, the mob will assuredly return with renewed strength, according to many organized-crime experts.

Indeed, American and European law-enforcement officials see a parallel between efforts to eradicate the Mafia in the United States and in its birthplace, Sicily. An unremitting campaign in the last 15 years by the Italian government against the Sicilian Mafia resulted in the imprisonment of more than 100 leaders and members.

But the crackdown cost the lives of ten top prosecutors and police commanders, who were murdered by the Mafia. And, after a period of disarray the Sicilian Mafia still thrives.

The American Mafia's traditional rackets have been illegal gambling, loansharking and labor racketeering in the construction, trucking and garment-manufacturing industries. Recently, the mobsters also created environmental havoc through widespread illegal dumping of toxic wastes that endanger water systems and agricultural areas.

Authorized toxic waste disposal is a costly procedure for garbage-removal companies and enormous profits can be made by ignoring mandated procedures. Investigations in New York State, New Jersey and Pennsylvania have uncovered numerous instances of illegal dumping of contaminated materials in rivers and isolated areas by companies suspected of being linked to Mafia figures.

Organized-crime experts say that the Mafia's recent difficulties were caused by these principal developments:

• In New York, John J. Gotti's swashbuckling and chaotic reign as boss of the Gambino crime family focused extraordinary law enforcement attention on him that ended with his conviction and sentence to life imprisonment. His removal and the arrests of his top lieutenants shattered the Gambino family, once the Mafia's premiere and wealthiest gang.
• Gotti's foremost national mob rival, Vincent (Chin) Gigante, the ruthless godfather of the super-secretive Genovese family, landed in prison despite his erratic masquerade as a mentally disturbed, harmless old man.
• In Philadelphia, internal carnage unleashed by a savage boss, Nicky Scarfo, ruined that city's mighty Bruno-Scarfo family.
• In New Jersey, Anthony (Caveman) Accetturo, the head of a wing of the powerful New York Lucchese family, became a prosecution informer and witness against his former allies. Accetturo, like other old-time gangsters, could no longer abide a new generation of greedy, undisciplined mobsters who, he asserted, violated the Mafia's unwritten code of honor by trying to kill him and other veterans to gain control of the family's lucrative rackets.
  

Throughout the country, several mob bastions have been reduced to a handful of aging relics or inexperienced wannabes. In Cleveland, Milwaukee, St. Louis, Kansas City, once robust strongholds, the ranks have shrunk to a dozen or so "made men," soldiers who are inducted into the mob with ritualistic blood oaths vowing eternal secrecy and loyalty under penalty of death.
In Los Angeles, investigators refer to the enfeebled survivors as "Mickey Mouse Mafia."

The mob's power in New York, however, has been the most difficult to eliminate because it is the only region with seven separate families, five based in the city and two in New Jersey. When one family was removed from a racket it controlled, the vacuum often was filled by another family.

The FBI and Justice Department are now equally concerned about the dangers confronting the nation from emerging ethnic crime organizations. A key question is whether the newcomers, principally Russians and Asians, will develop into menacing criminal forces capable of forging the networks of sophisticated rackets that are the Mafia's hallmark.

These new groups, however, rely mainly on a single specialty: narcotics, extortion, gambling or frauds. They lack the connections and knowledge of businesses and labor unions that enabled the Mafia to infiltrate enterprises like the garment, construction and waste-removal industries and siphon billions of dollars in kickbacks and inflated contracts.

Additionally, these newcomer are loosely knit gangs without firm leadership. In contrast, Mafia families were founded on ancient rules that prescribed a code of behavior for members and, most important, an organizational structure of command that usually allowed for a smooth transition even after a boss died of natural or unnatural causes.

Experts warn that the American Mafia's new crop of leaders will probably not repeat the mistakes of their immediate predecessors. Moreover, bookmaking and loansharking have always been staple cash cows for the mob and they continue to enrich survivors in the damaged families. Gambling and loansharking operations -- almost impossible to wipe out -- sustain the families and provide seed money for reviving old rackets and developing new ones.