One night, it might be a midnight raid by Israeli troops to arrest an elderly Islamic cleric; on another, the thunderous blast of a suicide bomber's home being blown up. Or it might be a precision daylight strike with helicopter-fired missiles that cuts a car and its occupants to pieces. Or the deafening echo of tank shells ringing through the cinderblock warren of a crowded refugee camp.
For nearly a month now, Israel has been waging its most concerted military campaign in memory against the Islamic Resistance Movement, or Hamas -- a battle that is being fought primarily on the radical group's home turf, the gritty urban neighborhoods and tumbledown villages of the Gaza Strip.
Since Feb. 16, Israel has killed at least two senior Hamas figures and nearly a dozen lesser activists, arrested scores of fugitives, temporarily occupied a dune-filled swath of northern Gaza and repeatedly sent tanks, helicopters and snipers into the mazelike alleys and mosque-lined thoroughfares of areas that are considered Hamas strongholds.
The government of Israeli Prime Minister Ariel Sharon has indicated that the drive against Hamas will intensify. Defense Minister Shaul Mofaz declared over the weekend that Hamas, particularly in Gaza, has become "an unrestrained monster of terrorism."
"There is a fear it will keep getting stronger and stronger and control everything in the Gaza Strip," he said.
But within Israel as well as overseas, alarms are being raised about the campaign's mounting cost in Palestinian civilian lives -- particularly during this volatile time of countdown to a possible U.S. war with Iraq.
Some observers are warning that Israel could find itself drawn into a quagmire in Gaza reminiscent of its long and bloody occupation of southern Lebanon, and are expressing doubts that this ongoing display of military might is dealing Hamas' shadowy infrastructure a real or lasting blow.
"I think Israel is not taking into consideration the full price that might be involved in a campaign of this type against Hamas," said Shaul Mishal, a Tel Aviv University professor who has long studied the group and its tactics. Sharon's government, he said, "is missing the important strategic dimension of all this."
Hamas, whose suicide attacks have killed hundreds of people during nearly 2 1/2 years of fighting, struck again last week with a bus bombing in the northern port city of Haifa that killed 16 people besides the bomber, many of them students.
In the wake of Israel's "targeted killing" last week of one of the group's leading ideologues -- Ibrahim Makadmeh, who died along with three bodyguards when Israeli helicopter gunships obliterated his car with missiles -- Hamas threatened to begin assassinating Israeli political leaders, including members of parliament.
"Israel has opened a new front in this battle, and it will find the consequences terrible," said Abdulaziz Rantisi, one of the group's senior political leaders.
In Gaza, where Israeli troops and Palestinian gunmen have been fighting pitched battles several times a week amid ramshackle homes jammed together, the civilian toll has been heavy.
More than 90 Palestinians have been killed in Gaza since the start of the year, according to Israeli human rights groups. A precise breakdown of civilians and combatants is impossible, but civilians are thought to account for at least a third of the dead, who in recent weeks have included a Palestinian woman who was nine months pregnant and at least five children under age 16.
In an editorial headlined "Senseless Killings," the Israeli daily Haaretz charged last week that army operations in Gaza were being carried out with "reckless abandon." Twice last week, after raids in Gaza that killed 22 people, the White House urged Israel to exercise greater care to avoid harming innocent Palestinians.
Since its inception in the late 1980s, Hamas has been inextricably linked to Gaza. The movement was born here, coalescing around a few charismatic Muslim preachers like Sheik Ahmed Yassin, together with a hard core of young fighters then waging the Palestinians' first intifada, or uprising.
Here in its heartland, Hamas' prestige and popularity are part of the landscape.
Its slogans dominate Gaza's graffiti-daubed walls, crowding out the colorful murals of rival groups. Enormous crowds turn out for its rallies and funeral marches. Posters of Hamas shahids, or martyrs, adorn schoolroom walls. At night, the group's self-appointed sentries -- masked men in camouflage uniforms cradling AK-47s -- patrol the darkened streets of cities and towns.
Yassin, the group's spiritual leader, is a revered public figure. Paralyzed since a childhood accident, he holds court from his wheelchair while devout young followers gently adjust his white head scarf. All of the female journalists who interview him are required to don an all-enveloping chador.
Until the last year or so, the power of Hamas had always been held in check by Palestinian Authority President Yasser Arafat and his Fatah faction. But Israel, through its efforts to marginalize Arafat, may have unwittingly tipped the scales in favor of Hamas, particularly in Gaza.
Confined by Israel to the West Bank city of Ramallah, the Palestinian leader has not set foot in Gaza for nearly two years. His seaside headquarters in Gaza City was wrecked months ago by Israeli missiles, and his once-formidable security apparatus in Gaza has crumbled.
Hamas, by contrast, has prospered. From the start of the current intifada, it has spearheaded a campaign of suicide bombings, which have become the most feared weapon of the Palestinians and the single greatest cause of Israeli deaths in 29 months of fighting. Other militant groups, including Islamic Jihad and the Fatah-linked Al Aqsa Martyrs Brigade, launched their own bombing campaigns at least partly in imitation of what was seen as the high-profile success of Hamas.
Over the years, the movement has sunk deep social roots. Hamas-run schools and clinics are a lifeline for Gaza's poor. And as the fighting grinds on, the reach and appeal of the group's radical ideology have broadened.
In the Gaza City suburb of Tufah, where an Israeli incursion last month left 11 people dead, Sami Hilo's eyes reddened as he gazed at the spot where his two older brothers died.
Neighbors and family said the Hilo brothers, 25-year-old Said and 21-year-old Ala, had no connection with Hamas or any other militant group. Both had been members of the Palestinian national soccer squad.
"Before, I wanted to be a soccer player like them," said Sami, 17. "Now, if someone gave me a suicide belt and told me to blow myself up next to Sharon, I would do it."
The Israeli army says one of its main objectives in Gaza is to limit the ability of Hamas to fire short-range Kassam rockets at Israeli towns. But rocketing continued even while Israeli tanks spent four days dug in at one of the prime launching spots in northern Gaza. Thus far, the crude homemade rockets have been mainly a psychological weapon, causing minor damage and few injuries.
Israeli officials have asserted that resentment of Hamas is beginning to build in the neighborhoods it uses as its base, with people holding the militants responsible for provoking Israeli raids. But it is difficult to find any evidence of that on the ground.
At the smoldering, rubble-strewn scenes of Israeli strikes, bitterness and blame are inevitably directed at Israel, not Hamas.
"This is our land, and Hamas is defending it," said 60-year-old Amneh Saleh, who was left homeless after an Israeli raid last week in the Jabaliya refugee camp. "Who are the terrorists? Israel, Israel!"
Israel's killing last week of Makadmeh, the highest-ranking Hamas political figure targeted to date, could usher in an even more high-stakes confrontation with the group, the members of whose top political echelon all live within a few miles of one another in Gaza City.
But the prospect of being targeted does not seem to faze its leaders.
Yassin, asked last week whether he expected to die at Israel's hands, paused before replying in his high-pitched, whispery voice.
"For 50 years," he said, "I have dreamed only of martyrdom."