JERUSALEM — Israel massed troops outside the Gaza Strip late Thursday, signaling that it was prepared to send in ground forces to engage Hamas militants who bombarded the Jewish state with more than 200 missiles and killed at least three people.
The escalating violence between archenemies Israel and Hamas, which launched scores of rockets into southern Israel in retaliation for a Wednesday airstrike that killed the Palestinian group's military chief, has sparked concern of all-out warfare in a Middle East already roiled by Syria's civil war and protests in the wake of the Arab Spring.
Israeli Prime Minister Benjamin Netanyahu made clear he was ready to expand the offensive.
"No government would tolerate a situation where nearly a fifth of its people live under a constant barrage of rockets and missile fire, and Israel will not tolerate this situation," Mr. Netanyahu said. "This is why my government has instructed the Israeli Defense Forces to conduct surgical strikes against the terrorist infrastructure in Gaza.
"And this is why Israel will continue to take whatever action is necessary to defend our people," he said.
Several Israeli tanks, armored vehicles and buses carrying soldiers moved toward the border late Thursday after a call-up of reservists for possible action in Gaza. Military officials said as many as 30,000 soldiers could be drafted in the call-up action.
"The question [of all-out warfare] comes down to whether Hamas will give in or not," said Daniel Byman, deputy director of the Saban Center for Middle East Policy at the Brookings Institution in Washington. "If it continues rocket attacks, it will be hard for Israel to cease its attacks, so this could escalate."
Hamas Prime Minister Ismail Haniyeh eulogized Hamas military chief Ahmed Jabari, whom Israel assassinated, in a televised speech Thursday night.
"What a martyrdom and what a glorious day," Mr. Haniyeh said. "Congratulations. Rest in peace. Feel blessed."
He said Palestinians remained steadfast and defiant during the 22 days of the last Israel-Gaza war in 2008 and 2009 and could hold out even longer. More than 1,400 Palestinians were killed in that war.
The heaviest fighting in four years also has killed 16 Palestinians in two days and brought life to a standstill on both sides of the border. School has been canceled, and many civilians were huddling indoors.
In Tel Aviv, air-raid sirens and a rocket explosion were heard Thursday night for the first time since fighting with Gaza militants began Wednesday. Israeli officials said the rocket exploded in an open area in Bat Yam, a town four miles to the south, without causing casualties or damage.
Israeli aircraft were reported to have attacked 320 Gaza Strip targets, including weapons arsenals, workshops, command posts, tunnels and rocket-launching sites.
Tanks firing from inside Israel and gunboats off Gaza's coast also participated in the attacks.
Except for a small number of targeted assassinations of militant leaders, the Israelis have attempted to avoid Palestinian casualties unlike their incursion four years ago, which brought accusations of war crimes.
Meanwhile, Egypt – one of two Arab states that have peace deals with Israel – announced that Prime Minister Hesham Qandil would visit the Gaza Strip on Friday in an expression of solidarity with the Palestinian territory.
The plan was announced after Washington urged Cairo to exert its influence in the region to stop the violence.
Israel's relationship with Egypt may become the biggest casualty of the violence in Gaza, analysts said. Egyptian President Mohammed Morsi has come under increasing pressure from his Muslim Brotherhood base to cancel the 1979 peace treaty with the Jewish state.
The Brotherhood, which had been banned in Egypt, came to power after Arab Spring protests ousted President Hosni Mubarak and the Islamist group's candidates won subsequent parliamentary and presidential elections.
"It is not just that Morsi is being pulled by the Brotherhood. His own impulses are, from all perspectives, to act irresponsibly," said Eric Trager, an Egypt analyst at the Washington Institute for Near East Policy.
"Morsi would try to use this flare-up to justify a breakup of relations with Israel. He is constrained from doing so, however, due to the cautiousness of his national security and diplomatic professionals, as well as by the reality that the Brotherhood doesn't want a confrontation with Israel now," Mr. Trager said.
Mr. Byman said Mr. Morsi can handle pressure from within the Muslim Brotherhood and will seek "lesser ways to show his anger at Israel."
Iron Dome defense
President Obama discussed developments in Gaza over the phone Wednesday with Mr. Morsi and Mr. Netanyahu, with whom the American president has a frosty relationship.
Mr. Obama reiterated "the United States' support for Israel's right to self-defense in light of the barrage of rocket attacks against Israeli civilians," a point he also made in talks with Mr. Morsi.
A White House statement said Mr. Obama and Mr. Morsi agreed on the importance of de-escalating the situation.
The Saban Center's Mr. Byman said the U.S. role should include asking Egypt to rein in Hamas.
"Obama must communicate to Morsi that using Israeli-Palestinian fighting to unravel the Israeli-Egyptian relationship is both illogical and unacceptable," Mr. Trager said. "He should make it very clear that any significant downgrade in Egyptian-Israeli relations by the Morsi government will be met by a cutoff of [U.S.] aid."
The U.S. had given Mubarak $1.3 billion in annual aid in exchange for keeping the peace with Israel.
On Thursday, Israel suffered its first casualties in the conflict when a rocket struck a four-story apartment building in the southern town of Kiryat Malachi, killing three people and wounding seven others, including three children.
Hamas and other Gaza militant groups fired more than 200 rockets Thursday, with Beersheba, Israel's largest city in the south, the principal target. Most landed without causing damage, and some were intercepted by Israel's air defense system.
Israeli officials praised the performance of their Iron Dome missile defense system, which they said intercepted half the rockets.
Iron Dome's radar is able to determine from a rocket's trajectory whether it will hit a populated area and intercept it. The system ignores rockets with trajectories that indicate they will hit open areas.
Some Israeli commentators have suggested that the attack on Gaza is being driven with an eye on domestic politics: Mr. Netanyahu is up for re-election in January.
"Prime Minister Benjamin Netanyahu is interested in neutralizing every possible rival, and Defense Minister Ehud Barak is fighting for enough votes to return to the Knesset," Aluf Benn, editor-in-chief of Israel's liberal Haaretz newspaper, wrote in an editorial. "A war against Hamas will wipe out the electoral aspirations of the ditherer, [former President] Ehud Olmert, whose disciples expected him to announce his candidacy this evening and it will kick off the agenda the 'social and economic issue' that serves the Labor Party.
"When the cannons roar, we see only Netanyahu and Barak on the screen, and all the other politicians have to applaud them," Mr. Benn added.
Ashish Kumar Sen in Washington contributed to this article, which is based in part on wire service reports.