A careful campaign of deception ensured Israel was caught off guard when the Palestinian Islamist group Hamas launched its devastating attack, enabling a force using bulldozers, hang gliders and motorbikes to take on the Middle East's most powerful army.

Saturday's assault, the worst breach in Israel's defences since Arab armies waged war in 1973, followed two years of subterfuge by Hamas that involved keeping its military plans under wraps and convincing Israel it did not want a fight.While Israel was led to believe it was containing a war-weary Hamas by providing economic incentives to Gazan workers, the group's fighters were being trained and drilled, often in plain sight, a source close to Hamas said.

This source provided many of the details for the account of the attack and its buildup that has been pieced together by Reuters. Three sources within Israel's security establishment, who like others asked not to be identified, also contributed to this account.

"Hamas gave Israel the impression that it was not ready for a fight," said the source close to Hamas, describing plans for the most startling assault since the Yom Kippur War 50 years ago when Egypt and Syria surprised Israel and made it fight for its survival.

"Hamas used an unprecedented intelligence tactic to mislead Israel over the last months, by giving a public impression that it was not willing to go into a fight or confrontation with Israel while preparing for this massive operation," the source said.

Israel concedes it was caught off guard by an attack timed to coincide with the Jewish Sabbath and a religious holiday. Hamas fighters stormed into Israeli towns, killing 700 Israelis and abducting dozens. Israel has killed more than 400 Palestinians in its retaliation on Gaza since then.

"This is our 9/11," said Major Nir Dinar, spokesperson for the Israeli Defence Forces. "They got us."

"They surprised us and they came fast from many spots - both from the air and the ground and the sea."
Osama Hamdan, the Hamas representative in Lebanon, told Reuters the attack showed Palestinians had the will to achieve their goals "regardless of Israel's military power and capabilities."