Hamas fighters are scattered in cells across the Gaza Strip, launching rockets, ambushing Israeli soldiers, and vanishing into tunnels and bunkers to escape airstrikes on a pummeled terrain of shattered buildings and bodies curled and crumpled in the streets.

As the Israeli incursion rumbles into a 17th day, witnesses in Gaza and analysts portray the Islamic militant group as battered but defiant. Its walkie-talkie networks bleep and scratch through alleys, and its fighters, many in civilian clothes, move with the stealth of urban guerrillas, booby-trapping neighborhoods, communicating through e-mails, text messages and whispers in marketplaces.

But although Hamas' militant wing had been preparing for an Israeli assault for years, the enemy's firepower has been devastating and some analysts say Gaza can't endure much more destruction. Government buildings have been razed and more than 1 million residents in the seaside enclave are without electricity. The Israel Defense Forces say that at least 300 militants have been killed, others are defecting and the number of rockets launched into Israel in recent days has declined significantly.

The Israeli media quoted an army official Sunday as saying that a high-ranking Hamas commander, Amir Mansi, was killed by Israeli fire when he tried to launch mortar rounds by himself after his fighters refused to help him. Israel has prevented international journalists from entering Gaza, and battlefield reports cannot be independently confirmed.

Hamas denies any loss of resolve. A senior official, who asked not to be named, said Sunday that only 30 of the group's fighters had been killed. "Hamas fighters are calm and don't want to be drawn toward Israeli troops," the official said. "We're waiting for the Israelis to advance toward our strongholds, then we'll fight. Hamas' power has not been harmed."

On Saturday night, as Israeli troops and tanks moved along the southwest edge of Gaza City, a witness spotted Hamas fighters, who hadn't been seen for much of the day, preparing to attack with rocket-propelled grenades and machine guns. The witness reported that the militants were organized and communicated in codes, and that later ambulance and civil defense workers responded quickly to areas that had been set aflame by Israeli shelling in fierce fighting.

But Hamas, which seized control of Gaza after a unity government with rival Fatah fell apart in 2007, is operating in a hemmed-in landscape tattered by airstrikes and limned with smoke and suspicion. Days and nights are spent attempting to outmaneuver Israeli forces and to control Fatah sympathizers or alleged collaborators, scores of whom are under house arrest or have been systematically shot in the legs. Hamas fighters recently stormed an Internet cafe in Deir al Balah and hauled away a man accused of spying.

Despite political and military barrages on many fronts, Hamas' political wing, led by Khaled Mashaal from his base in Syria, is still intact, denouncing Israel in speeches and dispatching delegations to Egypt to negotiate a possible cease-fire. Most of its top officials in Gaza, however, have gone underground and may be too isolated to assess the severity of the conflict. Yet civil duties, such as traffic control in some towns, are being carried out, the Hamas-led government has prevented price gouging, and the movement's radio and TV stations are broadcasting.

"The breakdown is far less complete than what one sees watching the TV or what Israel had hoped for," said Mouin Rabbani, a Jordanian-based analyst and expert on Hamas. He added that the enclave's infrastructure had been pounded, but that its civil and political leadership have retained "their capacity to control the Gaza Strip. . . . I can't believe anyone in the Israeli government seriously thinks they can eradicate Hamas."

The question is: How much longer can Hamas and Gaza's 1.5 million Palestinians endure the Israeli offensive? About 880 Palestinians, more than a third of them women and children, have been killed. That number and sustained Israeli military pressure have left Hamas with difficult choices. Neither side has shown interest in a cease-fire, but if Hamas were to agree to one without winning Israeli concessions, such as ending the 18-month blockade of Gaza, there probably will be criticism that weeks of bloodshed and ruin brought nothing. But if Hamas keeps fighting, what can it expect to win from an enemy with a superior military?

"Hamas is thinking that after all the attacks and the deaths of so many, they want something to show for it and not to return to the same point they were at in the beginning," Adnan abu Hasna, spokesman for the United Nations Relief and Works Agency in Gaza, told Israeli radio. "I think Hamas feels that if they accept a cease-fire now, this will be an even greater defeat than the military defeat."

In the towns and cities of Gaza, some are beginning to condemn the organization's tactics.

"If Hamas cares for its own people, they will not continue doing what they're doing," said Abu Haythen. "The world does not recognize Hamas. The Arabs don't recognize them. It is only since they have come to power in Gaza that we have seen destruction, blockades and bloodshed. This is the curse of their brutality."

However, Abdullah Kassab, a sophomore at the Islamic University in Gaza City, said Hamas was not to blame.

"Hamas is not the reason we are undergoing this," he said, referring to Israel. "We know we are not alone. The Arab and Muslim nations back us. Hamas is fighting for its destiny. It's a 'to be or not to be' battle and we must endure what all occupied peoples endure."

Hamas has long balanced its radical Islamist views against the Palestinian dream of statehood. The group's military wing, which is closely aligned to the leadership in Syria and is influenced by Iran and the militant Hezbollah organization in Lebanon, has gained a stronger voice. This was evident when top military commander Ahmed Jabari was recently named as a ranking member in Gaza's political echelon led by Ismail Haniyeh, who is widely viewed as a pragmatist. That militant tilt is likely to determine when, or if, Hamas accepts an end to the fighting.

"It's possible that Hamas' political arm will accept a cease-fire while the military arm will keep on fighting," said Anat Kurz, senior research fellow at the Institute for National Security Studies in Tel Aviv. "The higher [military] leadership of Hamas is underground, and there's a general assessment that they don't know what's going on above the surface. . . . If they do know what's going on, maybe they feel their backs are to the wall and they have nothing to lose."

The head of the Israeli Security Agency, Yuval Diskin, reported in a government briefing Sunday that Hamas' abilities were dwindling and its leaders were hiding in hospitals and bunkers and stealing humanitarian aid. He said that before the Israeli offensive began Dec. 27 the group was firing 100 to 200 rockets daily into southern Israel. In recent days, he said, Hamas has launched about 20 rockets a day. At least 13 Israelis have been killed since the offensive began: 10 soldiers, four of them from "friendly fire," and three civilians.

"Hamas has suffered many losses and has taken a harsh blow to its long-range firing capabilities -- and this on top of damage to its depots, production lines and to its militants' maneuvering abilities," Diskin said.

Israel, however, has not accelerated its ground advance deeply into Gaza City and other urban areas, where Hamas fighters, who know the geography and have reportedly booby-trapped passageways, probably would inflict higher casualties. There was heavy fighting Sunday in towns and neighborhoods at the edge of Gaza City, but Israel appeared to not push into the final phase of its assault.

"Israel is fighting a military war while Hamas is fighting a political war," said Mohammed Abdel Salam, a strategic analyst with Al Ahram Center for Political and Strategic Studies in Cairo. "Hamas is conducting very limited military operations that would allow it to survive until the Arab and international communities intervene. Hamas is using its huge civilian losses to pressure the Israelis and to embarrass all their Arab adversaries."