Palestinian rockets threatening Israeli cities, Islamic fighters streaming into Gaza and planes slamming into Tel Aviv skyscrapers figured high on Netanyahu's roster of post-pullout risks as he geared up for an expected leadership challenge.
"The ones who really understand what I am saying are the terrorists, and they are cheering because we are letting them set up an independent terrorist base (in Gaza)," Netanyahu said, addressing the Knesset to explain his reasons for resigning.
His speech coincided with opinion polls that found Netanyahu, 55, would best Sharon, 77, in a contest to head the right-wing Likud party if a vote was held now, although surveys show a majority of Israelis back the pullout.
Hitting back, Sharon accused Netanyahu, who originally supported the plan to evacuate all 21 Gaza settlements and four of 120 in the West Bank, of ducking responsibility for "what might be the most complex step" Israel has ever taken.
Describing the resignation as "an act of fleeing", Sharon, a former general, told Channel One television: "I certainly wouldn't give it a special military decoration."
MISSILE CRISIS?
Netanyahu, prime minister from 1996 to 1999, took particular aim at Israel's agreement for construction of a seaport in Gaza, a project key to improving the impoverished territory's economy.
Palestinian weapons ships would head for the port, Netanyahu said, drawing an analogy with Soviet vessels that brought missiles to what he called "the port of Cuba" in a 1962 crisis of atomic brinkmanship with the United States.
"These missiles will reach not only Ashkelon but also Ashdod," he said, referring to two cities on Israel's Mediterranean coast, respectively 15 km (nine miles) and 30 km (18 miles) north of Gaza.
Israel's navy keeps close watch on Gaza's coastline and has intercepted several Palestinian weapons ships.
But Israeli security officials have voiced concern Palestinian militants could make improvements to makeshift rockets that have hit Israeli border towns or smuggle longer-range Katyushas overland from Egypt.
Palestinian President Mahmoud Abbas, who declared a cease-fire along with Sharon in February, has demanded militants cease rocket attacks on southern Israel.
Netanyahu cited Gaza airspace, which Israel intends to continue to control under interim peace deals, as another crucial security issue.
"The Palestinians are saying ... 'if you control the airspace, the (Israeli) occupation has not ended'," he said.
Urging the Israeli government to stand firm, Netanyahu added: "Planes, such as those that slammed into the twin towers (in New York on September 11, 2001) can enter that airspace. We also have some towers."
The Palestinian Authority is seeking to rebuild and reopen Gaza international airport after the Israeli evacuation.
In his speech, Netanyahu predicted a Palestinian-governed Gaza Strip would be a magnet for Islamic fighters.
"There is a worldwide enemy, and they will stream here - they are already arriving - from Syria, Afghanistan and Iraq," he said, giving no indication how they might have crossed Gaza's Israeli-controlled borders. "al Qaeda has already announced it will open a branch here, and while I think it could still take some time, they too will come," Netanyahu added.