In the six years since Israel ended its military occupation of southern Lebanon, it watched warily as Hezbollah built up its military presence in the region. When Hezbollah militants kidnapped two Israeli soldiers last week, the Israeli military was ready to react almost instantly.

"Of all of Israel's wars since 1948, this was the one for which Israel was most prepared," said Gerald Steinberg, professor of political science at Bar-Ilan University. "In a sense, the preparation began in May 2000, immediately after the Israeli withdrawal, when it became clear the international community was not going to prevent Hezbollah from stockpiling missiles and attacking Israel. By 2004, the military campaign scheduled to last about three weeks that we're seeing now had already been blocked out and, in the last year or two, it's been simulated and rehearsed across the board."

More than a year ago, a senior Israeli army officer began giving PowerPoint presentations, on an off-the-record basis, to U.S. and other diplomats, journalists and think tanks, setting out the plan for the current operation in revealing detail. Under the ground rules of the briefings, the officer could not be identified.

In his talks, the officer described a three-week campaign: The first week concentrated on destroying Hezbollah's heavier long-range missiles, bombing its command-and-control centers, and disrupting transportation and communication arteries. In the second week, the focus shifted to attacks on individual sites of rocket launchers or weapons stores. In the third week, ground forces in large numbers would be introduced, but only in order to knock out targets discovered during reconnaissance missions as the campaign unfolded. There was no plan, according to this scenario, to reoccupy southern Lebanon on a long-term basis.

Israeli officials say their pinpoint commando raids should not be confused with a ground invasion. Nor, they say, do they herald another occupation of southern Lebanon, which Israel maintained from 1982 to 2000 -- in order, it said, to thwart Hezbollah attacks on Israel. Planners anticipated the likelihood of civilian deaths on both sides. Israel says Hezbollah intentionally bases some of its operations in residential areas. And Hezbollah's leader, Hassan Nasrallah, has bragged publicly that the group's arsenal included rockets capable of bombing Haifa, as occurred last week.

Like all plans, the one now unfolding also has been shaped by changing circumstances, said Eran Lerman, a former colonel in Israeli military intelligence who is now director of the Jerusalem office of the American Jewish Committee.

"There are two radical views of how to deal with this challenge, a serious professional debate within the military community over which way to go," said Lerman. "One is the air power school of thought, the other is the land-borne option. They create different dynamics and different timetables. The crucial factor is that the air force concept is very methodical and almost by definition is slower to get results. A ground invasion that sweeps Hezbollah in front of you is quicker, but at a much higher cost in human life and requiring the creation of a presence on the ground."

The advance scenario is now in its second week, and its success or failure is still unfolding. Whether Israel's aerial strikes will be enough to achieve the threefold aim of the campaign -- to remove the Hezbollah military threat; to evict Hezbollah from the border area, allowing the deployment of Lebanese government troops; and to ensure the safe return of the two Israeli soldiers abducted last week -- remains an open question. Israelis are opposed to the thought of reoccupying Lebanon.

"I have the feeling that the end is not clear here. I have no idea how this movie is going to end," said Daniel Ben-Simon, a military analyst for the daily Haaretz newspaper.

Thursday's clashes in southern Lebanon occurred near an outpost abandoned more than six years ago by the retreating Israeli army. The place was identified using satellite photographs of a Hezbollah bunker, but only from the ground was Israel able to discover that it served as the entrance to a previously unknown underground network of caves and bunkers stuffed with missiles aimed at northern Israel, said Israeli army spokesman Miri Regev.

"We knew about the network, but it was fully revealed (Wednesday) by the ground operation of our forces," said Regev. "This is one of the purposes of the pinpoint ground operations -- to locate and try to destroy the terrorist infrastructure from where they can fire at Israeli citizens."

Israeli military officials say as much as 50 percent of Hezbollah's missile capability has been destroyed, mainly by aerial attacks on targets identified from intelligence reports. But missiles continue to be fired at towns and cities across northern Israel.

"We were not surprised that the firing has continued," said Tzachi Hanegbi, chairman of the Knesset Foreign Affairs and Defense Committee. "Hezbollah separated its leadership command-and-control system from its field organization. It created a network of tiny cells in each village that had no operational mission except to wait for the moment when they should activate the Katyusha rocket launchers hidden in local houses, using coordinates programmed long ago to hit Nahariya or Kiryat Shemona, or the kibbutzim and villages."

"From the start of this operation, we have also been active on the ground across the width of Lebanon," said Brig. Gen. Ron Friedman, head of Northern Command headquarters. "These missions are designed to support our current actions. Unfortunately, one of the many missions which we have carried out in recent days met with slightly fiercer resistance."

Israel didn't need sophisticated intelligence to discover the huge buildup of Iranian weapons supplies to Hezbollah by way of Syria, because Hezbollah's patrons boasted about it openly in the pages of the Arabic press. As recently as June 16, less than four weeks before the Hezbollah border raid that sparked the current crisis, the Syrian defense minister publicly announced the extension of existing agreements allowing the passage of trucks shipping Iranian weapons into Lebanon.

But to destroy them, Israel needed to map the location of each missile.

"We need a lot of patience," said Hanegbi. "The (Israeli Defense Forces) action at the moment is incapable of finding the very last Katyusha, or the last rocket launcher primed for use hidden inside a house in some village."

Moshe Marzuk, a former head of the Lebanon desk for Israeli Military Intelligence who now is a researcher at the Institute for Counter-Terrorism in Herzliya, said Israel had learned from past conflicts in Lebanon, the West Bank and Gaza -- as well as the recent U.S. experiences in Afghanistan and Iraq -- that a traditional military campaign would be counter-effective.

"A big invasion is not suitable here," said Marzuk. "We are not fighting an army, but guerrillas. It would be a mistake to enter and expose ourselves to fighters who will hide, fire off a missile and run away. If we are to be on the ground at all, we need to use commandos and special forces."

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Since fighting started

-- Israeli air strikes on Lebanon have hit more than 1,255 targets, including 200 rocket-launching sites.

-- Hezbollah launched more than 900 rockets and missiles into northern Israel.

-- At least 330 Lebanese have been killed, including 20 soldiers and three Hezbollah guerrillas. Lebanese Prime Minister Fuad Saniora says 1,100 have been wounded; the police put the number at 657.

-- 32 Israelis have been killed, among them 17 soldiers, according to Israeli authorities. At least 12 soldiers and 344 civilians have been wounded.

-- Foreign deaths include eight Canadians, two Kuwaiti nationals, one Iraqi, one Sri Lankan and one Jordanian