GAZA CITY, Gaza Strip -- Israeli troops entered the Gaza Strip early today after Israeli aircraft bombed bridges and a power plant in an effort to force Palestinian militants to release a kidnapped Israeli soldier, or to punish them severely.
Israel's attack came in retaliation for the kidnapping and a day after one of the Palestinian militant groups involved in the soldier's capture claimed to have abducted a Jewish settler in the West Bank. The militants' raids and Israeli army responses are by far the most serious and destabilizing violence to occur since Israel's withdrawal last year from Gaza.
Before dawn, Israeli troops under the cover of tank shells took up positions east of Rafah, near Gaza's border with Egypt, and moved as Egyptian soldiers on the Egyptian side of the border watched, according to Palestinian officials quoted by wire services.
Israeli army officials said the operation was an attempt to rescue the kidnapped soldier, Cpl. Gilad Shalit, 19, after two days of efforts by Egyptian diplomats and the Palestinian Authority's president failed to gain his release. The Israeli military said it bombed the bridges "to impair the ability of the terrorists to transfer the kidnapped soldier." Knocking out the bridges would cut Gaza in two, Palestinian security officials said.
Before Israeli troops entered the area, a spokesman for the Popular Resistance Committees, a group with ties to the Islamic militant group Hamas, said that Shalit was alive and also claimed that the group had kidnapped the Jewish settler.
"The soldier is in a secure place that the Zionists cannot reach," said Mohammed Abdel Al.
Israeli aircraft fired missiles at Gaza's power station, engulfing its generators in flames that firefighters could not control, Palestinian officials told wire services.
For much of the day yesterday, Gazans tried to prepare themselves for fighting that seemed inevitable. Young Palestinian militants built earthen fortifications on roads near the border with Israel, and families stocked up on food and water. Hospitals added beds to surgery wards in expectation of casualties.
As Israeli action came to seem imminent, Palestinian officials announced that Hamas, which has refused to acknowledge Israel's right to exist, had reached an agreement with the rival Fatah party to form a national unity government that would recognize Israel. But within hours, Hamas officials were backing away from the announcement, denying that they had signed an agreement or altered their policies toward Israel.
Walid Awad, a spokesman for Palestinian Authority President Mahmoud Abbas, insisted last night that Hamas had signed an agreement based on an 18-point document written by Hamas and Fatah prisoners held by Israel.
"The document was signed by all political factions," Awad said. "Hamas has accepted a Palestinian state alongside the 1967 borders."
Awad added: "Hamas is trying to find a way out of it."
Hamas and Fatah have for weeks seemed deadlocked in bitter negotiations over the document. If the two factions indeed reached a settlement that recognizes Israel's right to exist, it could help end a crippling international economic blockade imposed after Hamas gained control of the Palestinian government in March.
But there was confusion yesterday over Hamas' position. Hamas officials denied that they had recognized Israel.
Awad said that under the agreement, Hamas would join a new government that would meet the conditions set by the United States and its allies for a resumption of aid: recognition of Israel's right to exist, renunciation of violence against Israel and acceptance of all previous agreements between Israel and the Palestinian Authority.
"Hamas does not recognize the legitimacy of the Israeli occupation," Awad said. "They recognize the existing state of Israel. They don't recognize the legitimacy of Israel in the long run."
Whatever their differences over recognizing Israel, Hamas and Fatah appeared to have put aside other disagreements yesterday in order to prepare for Israeli military action.
In the Shajaiyeh neighborhood of Gaza City, militants took up positions across from the headlights of Israeli vehicles, and Israeli attack helicopters hovered overhead.
"The Palestinians are prepared for whatever stupid thing Israel does," Abu Obeida, a spokesman for Hamas' military wing, told Israel Radio. "We are prepared and will not greet them with flowers."
"We have learned from previous invasions of Israel how to defend against them," said Abu Mujahad, 22, a Palestinian university student and member of Hamas' military wing, directing dump trucks unloading sand in northern Gaza - a weak defense against Israeli armored vehicles.
"Yes, it is a simple strategy, but this is our ability," he said, "We are depending on the support of Allah."
"We will not hold back on our efforts, and to our great sorrow, part of this price will be paid by the residents of the Gaza Strip," Haim Ramon, a senior Israeli Cabinet minister, told Army Radio before the attacks. "This strike will come, and it will be very painful. In order to stop this, I call on authorities in the Palestinian Authority to do all they can to bring Gilad home."
Although Israel frequently carries out air raids in Gaza, ground troops had entered the area only three times since Israel withdrew in September.
Secretary of State Condoleezza Rice urged Israel to "give diplomacy a chance."
A senior military officer told a committee of the Israeli parliament that Shalit was being held in the southern Gaza Strip and that the army wanted to prevent his being moved to Egypt, according to Israel Radio.
It also reported that Egypt had deployed more than 2,500 police and soldiers on its border with Gaza, fearing a rush by Palestinians out of Gaza if Israel launched an attack. Egyptian officials said the government asked Hamas to release the soldier, but that negotiations had made little progress.
"When Israel comes to invade us, we all help each other - Hamas, Fatah, Islamic Jihad, whatever," said Abu Mazen, who makes ice cream in Gaza's Jabaliya refugee camp but was helping Hamas with its preparations.
Dr. Ali Abed, 40, a surgeon at Khamel Edwan Hospital in Jabaliya, said doctors doubled the number of beds, even sending some patients home early to open up more space. The hospital had four surgeons on duty instead of the usual two.