The road, less than 50 yards wide, is bordered to the northeast by dilapidated houses of the densely populated Rafah refugee camp. To the southwest is the Sinai Desert, lightly patrolled along a border fence by Egyptian police.
Beginning Monday, in its largest push into the Gaza Strip since the 1967 Six Day War, Israeli tanks backed by helicopter gunships sealed off Rafah from the rest of the strip and began a systematic hunt for the tunnels and the contractors who build them.
Armored bulldozers have begun knocking down houses that the army says are used to hide tunnel openings. The demolitions have created a rubble-strewn theater of war in which at least 20 Palestinians, including 15 described by the army as gunmen, were killed yesterday. Hundreds of residents fled their homes carrying mattresses, plumbing fixtures, and virtually anything that fit on their backs.
The major incursion, heavy death toll, and wholesale displacement of people already defined as refugees have provoked an international outcry.
But the army, which says it has uncovered more than 80 tunnels along the Philadelphi Road in the last three years, maintains it has no choice but to act now before it is too late.
The army says that, while the tunnels have been used to transport automatic rifles, ammunition and explosives into the strip, heavier armaments, including Katyusha rockets, rocket-propelled grenades, and antiaircraft guns, could soon be coming through the pipelines.
Citing recent intelligence reports, Israel says it has information that the heavier weapons are being sent from Iran, through the Lebanese group Hezbollah, into Egypt and are destined for Hamas, Islamic Jihad, and other Palestinian extremist groups.
Islamic Jihad claimed responsibility for a rocket-propelled-grenade attack on the Philadelphi Road that killed five Israeli soldiers last week.
"Certainly, AK-47s and other light arms were getting in," Israeli army spokesman Jacob Dallal said. "But we are looking at a move toward Katyushas and antiaircraft weapons, and that indicated a change in the strategic balance that we are very concerned about it.
"Once a Katyusha gets into Gaza, it can easily reach Ashkelon," Dallal said.
Ashkelon, an Israeli city of 90,000, sits on the Mediterranean about 10 miles north of the Gaza Strip and includes a major electric-power station.
"It's not terribly pleasant to see Palestinians lose their homes, but the safety of our soldiers is everything. Israel can't ever give up that road," said Uzi Attiya, 42, whose home in the Jewish settlement of Rafi'ah Yam overlooked yesterday's fighting.
Moments after he spoke, a large explosion sent a plume of black smoke into the air just a few hundred yards away.
Even under Israeli Prime Minister Ariel Sharon's announced intention to eventually evacuate all 7,500 Jewish settlers from the Gaza Strip, Israel would maintain military control of the Philadelphi Road because it is seen as vital to Israel's security.
Over the weekend, Israeli officials said more than 100 Palestinian homes might have to be razed to create a buffer zone around the road.
Since then, more than 80 Rafah houses have been destroyed by Israeli troops, according to U.N. relief workers.
But the commander in charge of the operation said yesterday that clearing the way for a wider Philadelphi Road had not yet begun.
"This is not a declared intention of this operation," Col. Pinky Suarez told Israel Radio. "At this stage we have no intention of widening the Philadelphi route."
Contact reporter Michael Matza at 215-854-2405 or firstname.lastname@example.org.