Despite Indonesia's decision to allow foreign peacekeepers into violence-torn East Timor, the apparent complicity of the military in the death and destruction in the territory has conveyed a powerful message to other restive regions across the sprawling archipelago.

The message to Aceh, with its gas fields, to Irian Jaya, with its gold and copper mines, and to other places where separatist sentiment simmers is as simple as it is brutal: "This is what will happen if you, too, if you try to break away from the Indonesian state."

"It's pure revenge and extermination," said Ana Gomes, who heads the Portuguese mission here. "And at the same time, it's to teach a lesson to the others, the Acehnese and others."

For many outside Indonesia, it seems illogical, even inconceivable, that the military would risk this huge country's reputation -- jeopardizing urgently needed international economic aid as well as arms supplies and military ties -- to pursue its scorched-earth policy in East Timor. But for the Indonesian military, which sees itself as the protector of the nation's fragile unity, the domestic stakes are higher. They fear the country is falling apart.

If "you have a referendum [on independence] in East Timor, then the question is why can't you have a referendum elsewhere," said Michael Leifer, director of the Asia Research Center at the London School of Economics. "What they face in Aceh is far more problematic than in East Timor. You give up Aceh, and you open up a huge Pandora's box, because that really challenges the whole basis of Indonesian nationalism. For example, why should Sumatra and Java be joined together?"

It has been considered a success -- and a miracle -- that this 54-year-old country's first two presidents, Sukarno and Suharto, managed to hold together this diverse nation of 17,000 islands and hundreds of ethnic and linguistic groups. But the advent of democracy has loosed pent-up anger and feelings of ethnic and religious chauvinism. Moreover, a debilitating economic crisis has highlighted regional disparities, bringing new complaints from the more prosperous outlying islands that their resources are being drained to support populous, poorer Java, site of Jakarta, the capital.

Never before has the country's cherished national unity seemed so fragile. For 32 years, Suharto held this nation together with an iron grip and a fair amount of repression -- in much the same way that Tito ruled the old Yugoslav federation. But Suharto fell from power in May 1998, swept aside by a financial crisis that cheapened the currency and brought protesters into the streets. Suddenly, Indonesia's long-silent outer-island provinces began agitating for more autonomy.

The fear now, for Indonesia and the world, is of a Yugoslav-style break-up of Indonesia -- a "Balkanization" of its far-flung territories. In the world's fourth-most-populous nation, regional destabilization is a worrisome prospect, and that is why the military vehemently opposed President B.J. Habibie's offer to the East Timorese to choose, by referendum, whether to remain part of Indonesia or separate. That also is why -- once the decision was made -- that elements of the military worked covertly to undermine it, forming and arming militia gangs in East Timor to sow terror and try to intimidate voters.

East Timor itself may be unimportant; it is poor, has few natural resources and only 800,000 people, most of them Catholics in a predominately Muslim country. But many Indonesians fear that allowing East Timor to go its own way could set off a chain reaction of secessionist claims in the vast oceanic nation, long considered an anchor of stability in the region. "The president launched Indonesia on a course that was disastrous," said one seasoned diplomat.

In Aceh, a region at the northern tip of Sumatra, the separatist insurgency is far more volatile and violent than East Timor's ever was. Each day brings reports of soldiers being ambushed, of civilians killed in army sweeps and of thousands more left homeless. As Acehnese rebel commander Abdullah Syafii said in an interview just before the Aug. 30 vote in East Timor: "If East Timor gets its independence, then any other area that has been colonized by the Indonesian government has the right to its independence."

A smaller separatist movement is brewing in the mountains of Irian Jaya -- the western half of New Guinea -- where armed guerrillas are fighting for a "Free Papua," the area's name under Dutch colonial rule.

The Indonesian city of Ambon -- at the center of the famed Spice Islands -- has been so torn by clashes between indigenous Christians and Muslim migrants that the military has sealed off the devastated town.

Kalimantan, a mountainous region of central Borneo, is the site of massive refugee crisis following ethnic violence there earlier this year between indigenous Dayak and Malay peoples battling more recent migrant traders from Madura. Thousands of people there are still homeless, many living in government buildings and a soccer stadium.

As Marzuki Darusman of the National Human Rights Commission put it: "The issue now is whether the president is seen as being able to hold the country together."

For Indonesians, particularly on Java, the main island, the possibility of national disintegration is a concern that goes beyond nationalist pride. Java is home to 60 percent of the population, but the outer islands, as they are called, hold most of Indonesia's vast mineral wealth and economic strength -- from the coffee plantations of Timor and Sumatra to the famed tourist beaches of Bali. That economic disparity was underscored by the debilitating economic crisis and currency collapse that began in late 1997. While the crowded cities of Java sank deeper into poverty and misery, many of the outer islands prospered, taking advantage of increased commodity exports because of the devalued rupiah.

If the prospect of a fragmented Indonesia is frightening to Indonesians, it is a nightmare for a region that has prided itself on 25 years of stability. "It's so terrifying I don't even want to contemplate it," said a veteran diplomat from a neighboring country. "I can't imagine it."

Some fear that Balkanization here might also fuel separatist movements in other countries around the region or ignite new ones. Islamic secessionist movements have been waging war in the southern Philippines and in southern Thailand, which is already an arms conduit to Indonesia's Aceh province. There could be a new regional refugee crisis as people try to flee the fighting or are driven from their homes and lands.

Japan must worry about the navigability of the Malacca Strait, a key oil shipping lane along the Sumatra coast that links the Pacific and Indian oceans. An Australian diplomat here expressed fear that an overcrowded and poverty-ridden Java might become a menace to his country, which lies just to the south. The United States too would have to rethink a strategy in which the southern rim of East Asia has been an anchor of stability viewed against the flash points to the north -- the heavily militarized Korean peninsula and the Taiwan Strait.

"It's very incalculable," said Leifer, a Southeast Asia expert. "I would hate to think of what would be the cost in human terms if Indonesia broke up. People who believe in `unity in diversity' would be at each other's throats."

The Indonesian secessionist movements all have different origins. Predominantly Catholic East Timor, for example, has never been considered a truly integrated part of the nation since its annexation in 1976; the Acehnese have a long history of struggle and never fully succumbed to Dutch colonial occupation or Indonesian rule.

What is similar in both cases is that for much of the past three decades these problems have simmered, and the territories' grievances never have been properly addressed. "The . . . government swept under the rug many of the conflicts," said Salim Said, a political scientist and military analyst. "Religious problems, ethnic problems, race problems -- these were not allowed to be discussed. They said this was a harmonious society with no differences, but in reality we had all of them."

The military has been used to quell local upheavals, but it has often been criticized for its excesses, and repeated reports of human rights abuses have ended up making matters worse.

Many here blame Habibie for the East Timor crisis,thus sparking similar demands in Aceh and Irian Jaya. But Habibie said in an interview in early August that he viewed East Timor as a special case -- and thus suitable for an independence vote -- but that other secessionist movements would be dealt with firmly.

Most analysts believe the only way to maintain Indonesia's unity is by giving broader autonomy to all the provinces. Habibie has proposed just such a sweeping autonomy measure, but his transition government lacks the credibility to follow through, and the politicians who will dominate the new parliament, elected in June, are divided on how far to go.

"The longer we wait to solve these problems, the more likely they will trigger disintegration," said analyst Said. "It really depends on whether we have a credible government that the people trust."

Disparate Archipelago

Although most of Indonesia's 212 million people are Muslims, a sizeable minority is made up of hundreds of ethnic and linguistic groups. The nation has held together for 54 years, but, with East Timor voting for independence, there are fears the archipelago could splinter.

ACEH

Aceh was promised special autonomous status at indpendence in 1975, but Indonesia never followed through.

SULAWESI

Many Sulawesi feel isolated from Jakarta.

IRIAN JAYA

Tribal communities complain they had no say in the 1969 integration into Indonesia and rebels are fighting for independence.

AMBON

Area devestated by recent clashes between Christians and migrant Muslims.

KALIMANTAN

Thousands homeless from fights earlier this year between migrant traders from Madura and indigenous Dayak and Malay peoples.

JAVA

The hub of political and military power and home to 60 percent of the nation's people.

BALI

Predominantly Hindu. Many Balinese complain that most tourism revenue goes to Jakarta.

EAST TIMOR

Predominantly Christian area voted overwhelmingly for independence from Indonesia last month.