Israeli aircraft kept up a relentless string of attacks on Hamas-ruled Gaza on Tuesday, smashing a government complex, security installations and the home of a top militant commander as thousands of Israeli ground troops, backed by tanks and artillery, massed along the border and waited for a signal to attack.
Israeli Prime Minister Ehud Olmert told President Shimon Peres on Tuesday that the aerial phase of the operation is "the first of several" phases of attack that have been approved, an Olmert spokesman said.
Warplanes launched their bruising aerial offensive on Saturday after the Islamic Hamas defied Israel's warnings that it would not stand for the rocket barrages on southern Israel that resumed nearly two months ago, toward the end of a recently expired truce.
More than 360 Palestinians have been killed, most of them members of Hamas security forces but at least 64 of them civilians, according to the United Nations. The toll includes two sisters, aged 4 and 11, who perished in an airstrike on a rocket squad in northern Gaza on Tuesday.
Militants, battered but unbowed, have pressed on with their rocket and mortar assaults, killing three Israeli civilians and a soldier and bringing a widening circle of targets into their sights with an arsenal of longer-range missiles.
"Zionists, wait for more from the resistance," Hamas spokesman Ismail Radwan said in a text message to reporters, referring to militants' armed struggle against Israel.
The military estimated that nearly 10 percent of Israel's population of 7 million people is now within rocket range, shifting the battles closer to Israel's heartland. Of the four Israelis killed since the operation began Saturday, all but one were in areas that had not suffered fatalities before.
Fires blazed across the Gaza Strip's main city, Gaza City, where five government buildings were badly damaged in air attacks Tuesday. Rescue workers said 40 people were injured when warplanes dropped more than a dozen bombs on the government compound. It wasn't clear whether anyone was buried under the debris.
The campaign began Saturday when the air force hammered security facilities, then broadened to weapons-making and storage facilities, the homes of militant field operatives and government buildings that are the symbols of Hamas' power.
The initial wave of airstrikes took Gaza by surprise, targeting militants and Hamas security forces at key installations, often located in the midst of tiny Gaza's densely populated towns and cities.
But the government buildings targeted later were empty, as Gazans became fearful of venturing out into the streets. For Ziad Koraz, whose nearby home was damaged in the attack on the government compound Tuesday, that violence gratuitously put Gaza civilians at risk.
"More than 17 missiles were directed at an empty government compound, without regard for civilians who lived nearby," Koraz said. "We are people who live in peace and want to live in peace. If someone committed a crime, they should go after him, not after an entire nation."
The offensive began eight days after a six-month truce between Israel and the militants expired amid a barrage of Palestinian rocket fire. The offensive comes on top of an Israeli blockade of Gaza that has largely kept all but essential goods from entering the coastal territory since Hamas violently seized control June 2007.
Israel agreed to allow 100 trucks of humanitarian aid into Gaza on Tuesday, as well as five ambulances from Turkey, defense officials said. A Jordanian diplomat said 21 Jordanian army doctors and four field hospitals would be allowed to enter on Wednesday, though Israeli officials could not immediately confirm that.
Israel's navy on Tuesday turned back a boat of pro-Palestinian protesters who had hoped to enter Gaza to demonstrate against the Israeli blockade.
So far, warplanes and unmanned drones have dominated Israel's military operation. But the military has moved up thousands of infantry soldiers, dozens of tanks and artillery pieces. With the air force knocking off target after target, the big question looming over the operation is whether it will expand to include ground forces. The border area was declared a closed military zone on Monday, drawing a thick fog over operations in the area.
Olmert spokesman Mark Regev wouldn't comment on the prospects for a ground operation but said Israel would "continue keeping the pressure up on the Hamas military machine."
"This operation will continue until a new security reality can be created in the south, and those hundreds of thousands of Israelis who live in fear of Hamas rockets no longer have to live in that fear," Regev said.
Short of reoccupying Gaza, however, it was unlikely any amount of Israeli firepower could permanently stop rocket attacks. Past operations all failed to do so.
The militants have fired even while under the barrage of Israeli bombs and missiles, demonstrating with deadly effect the widening threat that is making larger cities farther inside Israel vulnerable. On Monday, a missile crashed into a bus stop in Ashdod, 23 miles (37 kilometers) from Gaza and only 25 miles (40 kilometers) from Israel's heartland in Tel Aviv.
The city of 200,000 is the largest in southern Israel.