For the Israelis of Kfar Saba (search), the high concrete wall dividing them from the West Bank is a salvation: It has halted the homicide bombings that cloaked their town in fear.

For the Palestinians of Qalqiliya (search), less than a mile away, it is a noose suffocating their once vibrant town.

Meir Toledano, a 52-year-old from Kfar Saba, nods approvingly at the barrier: "I live in peace now." Mohammed Hanini (search), 40, glares at it from the other side: "If I could pull it out with my teeth, I would."

Starting Monday, the International Court of Justice in the Netherlands will hear arguments on the legality of the barrier and decide whether to wade into the dispute. The U.N. General Assembly decided in December to ask the court for an advisory opinion after Israel ignored a resolution demanding the barrier be taken down.

Israel has challenged the judges' authority in the case, saying it is a political matter, and will not attend the hearings. It says that the barrier has greatly slowed homicide bombings and that the planned 450-mile route will be completed.

The United States and the European Union, while critical of the barrier's route, said the court's intervention would be inappropriate and could undermine peace efforts.

The Palestinians call it "the wall," the Israelis call it the "anti-terrorism fence." Most of it is a sandwich of fences, ditches, razor wire and high-tech sensors, but in Qalqiliya it is a two-story-high wall to stop snipers from terrorizing traffic on a highway on the Israeli side. An Israeli girl was killed in a shooting in June 2003 and a month later Palestinians fired at a car but no one was hurt.

It doesn't just cut off Qalqiliya from Israel; it encircles it to protect a nearby Jewish farming community inside Israel and a road used by West Bank settlers, the army said.

The Palestinians say Israel is building illegally on occupied land and using the barrier to grab areas they claim for a state. The 125 miles already built run mostly close to the "Green Line," the pre-1967 Mideast war boundary, but in parts dips as much as 4 miles into the West Bank.

Unbuilt sections could jut 14 miles, or more than one-third of the way across the West Bank.

It's "a human catastrophe," Palestinian Cabinet minister Saeb Erekat says — a juggernaut that keeps farmers from their fields, patients from their doctors and children from their schools.

Israel has lately acknowledged planning errors that unnecessarily disrupted Palestinian life and says it may move parts of the barrier closer to the Green Line to minimize hardship for Palestinians.

These second thoughts may be a sign of Prime Minister Ariel Sharon's continued ambivalence. The barrier wasn't his idea but his moderate predecessors'. Sharon initially opposed it because it would mean abandoning Jewish settlements on the West Bank side and would be seen as acknowledgment that Israel plans to give up the whole West Bank one day.

However, as homicide bombers kept attacking and a frightened public cried out for a solution, Sharon relented. Construction began in August 2002. Costing roughly $3 million a mile, it is one of the largest public works project ever undertaken by the Israeli government.

Its ripples spread far beyond. The appeal to the General Assembly and world court was supported by neighboring Jordan, which feared it would have to deal with a new wave of Palestinian refugees squeezed out by the fence.

Israel insists it is not drawing a political border, and says the barrier can be taken down or moved if a peace deal is reached.

Kfar Saba, a town of 85,000 about 10 miles northeast of Tel Aviv, was once intertwined with Qalqiliya, population 43,000, in a relationship that transcended the conflict. Palestinians from Qalqiliya went to Kfar Saba for work and to buy little luxuries. Israelis from Kfar Saba went to Qalqiliya to dine, buy produce and get their cars fixed.

Many in both towns talk of their friends across the divide.

"We lived together without any problem," said Bilal Mansour, 41, who owns a car repair shop in Qalqiliya.

But that relationship soured when violence erupted in 2000.

Five suicide bombers set out from Qalqiliya and killed 28 Israelis. Kfar Saba was the target of four bombings. It became lifeless. Many stopped riding buses, shopping at the mall and eating in restaurants.

Since the northern section of the barrier was completed in July, there have been no bombings and Kfar Saba has come back to life. The streets are filled with children on bicycles and parents pushing baby strollers.

"You can see the difference in the faces of the people. There's more joy," said Dedi Rahv, 52, an electrician.

A sharp drop in Israeli deaths since the start of construction has been attributed largely to the barrier, though analysts also cite other factors, including sporadic truce talks, the weakening of militant groups and better intelligence.

Though would-be bombers can still get into Israel through unbarricaded areas, the longer journey gives more time to catch them, said Col. Dany Tirza, the army's operations chief for the barrier.

In recent months, the army says, troops have cornered several militants with explosive vests trying to find their way around the barrier.

When the barrier is complete, Israel hopes it will be as secure as the one around the Gaza Strip, which no bombers have penetrated.

Palestinians see nothing but oppression in the construction, and have focused all their efforts on derailing it.

"It has become a symbol of occupation and apartheid, and for the sake of both people and for the future it must be removed," said Mustafa Barghouti, a Palestinian human rights activist.

Human rights groups say 7,000 acres of Palestinian land have been expropriated for the barrier, and about 100,000 trees uprooted.

Unless the route is changed, the barrier will affect nearly one-third of West Bank Palestinians, according to the United Nations: 274,000 Palestinians trapped in tiny enclaves and 400,000 more blocked from their fields, jobs, schools and hospitals.

The barrier has about 40 gates to ease disruptions, but opening times are irregular and permits to cross are hard to get, Barghouti and international human rights workers say.

Communities along other parts of the barrier are also suffering, particularly Arab suburbs of Jerusalem that have been cut off from the city.

Qalqiliya now feels like a ghost town.

More than 40 percent of stores and other business have closed, streets have emptied, unemployment has soared to 65 percent, and more than 80 percent of families are receiving international food aid, local officials say.

Farmers have trouble getting to their fields beyond the barrier, let alone delivering produce to West Bank markets. They can no longer sell to Israelis at all.

Bilal Mansour used to bring in about 2,500 shekels ($550) a day fixing Israeli-owned cars at the large garage he owns with his brother.

Now he takes a midday snooze on the grassy median of a four-lane road that once carried a constant flow of traffic between the town and Israel. It now dead-ends at the wall.

Mansour's nearby garage, with bays for 10 cars, sits empty. The car wash brushes are so dry and sunbaked after two years of idleness that they crumble to dust in his hand.

He makes between $11 and $55 a day on the few days when there is work. His family of six has stopped eating meat regularly, and he shaves only once a week to save on razors.

"If I could, I would sell and get out of here," he said.

Mansour blames Sharon and Palestinian leader Yasser Arafat for failing to reach an agreement, and the suicide bombers "who have ruined everything."

The military admits its haste in erecting the barrier led to some poor decisions that hit Qalqiliya especially hard.

While the wall will stay, the checkpoint controlling traffic into and out of Qalqiliya has been unmanned for weeks and will soon be dismantled completely, Tirza said. A tunnel is being built to help people move in and out of town, he said.

Sections elsewhere will be moved to reduce by about two-thirds the 11,000 people trapped between it and the boundary with Israel, the military said.

"We made mistakes, we realize that, and we are not ashamed to say we learned and we are adjusting it," Tirza said.

Outside the upscale Arim Mall in Kfar Saba, where two people were killed in a November 2002 suicide bombing, Israelis praised the barrier but mourned the death of their relationship with their sister town.

"Nobody wanted this wall," said Rahv, the electrician.