Australian troops call it "Nui Dat Hill," after a similar bluff manned by Aussie "diggers" in the Vietnam War. Here they are not on the lookout for black-clad Viet Cong, but for pro-Indonesian militiamen rumored to be massing by the thousands just across the mountain range for an assault on East Timor.

The first line of the static defense is a sandbag bunker that holds between four and six soldiers. A little more than three miles away, across the ridge line, is western Timor, part of a separate Indonesian province, where as many as 12,000 militiamen are said to be preparing for an attack. According to a militia defector named Silvestre, who sneaked over the border to warn the Australians, "They plan to kill every white man in Balibo."

There are now about 900 Australian-led international peacekeeping troops in the Balibo region, and they are alert but unconcerned. "We've been receiving a number of reports of 3,000 to 12,000 militia on the other side of the border getting ready to come and say hello to us," said Lt. Col. Mick Slater of the 2nd battalion of the Royal Australian Regiment. "I don't think it will ever eventuate."

He added, "If 3,000 militia come up here now, we wouldn't need any reinforcements. We'd have men to spare."

But they aren't taking any chances, especially after Silvestre's warning. Overnight, the Australian base camp was on high alert. No militia assault materialized, but sentries with night vision goggles did spot two men armed with assault rifles, wearing military uniforms and vests and moving with military-style precision on an obvious intelligence-gathering mission close to the camp's perimeter.

An officer said they came "very, very close"--within hearing range of the camp--but Australian army marksmen had them spotted with their night aiming devices. If they had raised their weapons, the militiamen would have been targeted instantly.

It wasn't the first such intrusion. "There have been a number of unsavory individuals trying to sneak into the town at night," Slater said. But, he added, confidently, "We own the night."

There was other apparent militia activity overnight in the sector. Two men from the hills entered one small village before dawn and set fire to the remaining huts there. There wasn't much left to burn, since the village had largely been incinerated. And the intruders, wearing military-style camouflage pants and T-shirts, were unarmed. But the incident showed how easy it is to cross the East Timor border and how even the current sense of security can be precarious.

Figuring out the militias' next move has become everyone's favorite guessing game. From their new stronghold in western Timor, they talk tough, planning a return to seek further revenge against East Timorese for voting overwhelmingly on Aug. 30 to become independent from Indonesia. That result prompted an Indonesian army and militia rampage that left East Timor's towns largely destroyed, its countryside depopulated and an untold number of people dead.

But as the Australian-led multinational peacekeeping force has begun fanning out across the territory, the militia threats have proven to be empty. There has not been a single encounter, and in every case the once feared militiamen have scattered when foreign troops arrived.

Most have fled across the border to the western half of Timor island, where they are reported to be regrouping and planning to return. But despite some colorful rhetoric from militia leaders such as Eurico Guterres, who said his followers were "thirsty for the blood of white people," there have been no clashes.

"Since we showed up, we haven't seen hide nor hair of them," said the crew commander of an Australian armored personnel carrier as he sat with his men at a checkpoint at Batugade, a deserted, mostly destroyed border crossing point. "They've obviously changed their tune. They're just a bunch of hot air, really."

In the five days since Australian troops have moved to the western parts of East Timor, they have acted quickly to consolidate their hold on an area once considered a militia stronghold.

Australian troops are constantly on patrol in Balibo, and they have taken over abandoned buildings. The field where a plaque was laid to mark East Timor's forced integration with Indonesia in 1976 is now the main Australian military camp. Around the plaque are parked armored vehicles with names like "Blast From The Past," "Bleeding Heart" and "Beer and Skittles," all beginning with the letter "B" for B Company.

The confidence of the peacekeeping forces was tested only when the militia defector, Silvestre, arrived. He walked across the jungle, he said, and told the troops who found him that he was forced to join a militia called Besi Merah Putih--Red and White Iron--in the days after the independence referendum.

"People turned up and threatened everyone and burned down their houses and told them if they didn't go to Atambua [in western Timor] they would be killed," said Silvestre, 23, through an Australian military interpreter.

The camps in Atambua, he said, are like armed prisons. "During the day, it's fairly normal, but at night, there are members of BMP and Aitarak [another militia group] walking around carrying weapons. . . . At night, they kill and rape people."

A few nights ago, Silvestre said, militia leaders Tavares and Eurico Guterres "called everybody together and said there would be an attack. . . . They planned to kill every white man in Balibo." He told the Australians that there were 10,000 militiamen at the border, "all very well armed," said the interpreter, Maj. David Kilcullen.

CAPTION: Maj. David Kilcullen, an Australian army interpreter, talks to an East Timorese man who said anti-independence militias forced him and his wife to flee across the border to western Timor.