"This is a long war...It requires lots of patience, sometimes endless restraint," Olmert was quoted as saying by Reuters.
"We have to know when to clench our teeth and to deal a decisive blow."
Israel has given the army a green light to launch a deeper incursion into northern Gaza, though there was no indication when it might begin, the Maariv newspaper reported.
This came after a deadline passed on Tuesday for Israel to accept a prisoner exchange offered by the three Palestinian resistance factions holding the soldier.
Israel launched its onslaught on Wednesday, June 28, destroying the Gaza Strip main power plant, three main bridges, water pipes, schools, universities, football pitches, tombs and the office of Haniya.
Israeli tanks and bulldozers also devastated vast swathes of olive trees, a main source of income to the Palestinian farmers.
About 5,000 troops and columns of Israeli tanks are stationed on the Gaza border in the largest Israeli offensive since it pulled out of the tiny coastal territory last September, ending a 38-year-occupation.
Switzerland, the depositary state for the Geneva Conventions, accused Israel of inflicting "collective punishment" on Palestinians. (Reuters)
While tanks and infantry massed along the Gaza Strip's northern border for a threatened ground incursion, Israel warned the governing Hamas that the "sky will fall on them" if Corporal Gilad was harmed.
"I want to stress, none of them will be immune," Olmert said.
His Interior Minister Roni Bar-On told Israel Radio: "Hamas well understands ... that the sky will fall on them if they harm Gilad Shalit."
Switzerland, the depositary state for the Geneva Conventions, asserted Tuesday Israel had broken humanitarian law by inflicting "collective punishment" on Palestinians.
"A number of actions by the Israeli Defense Force in their offensive against the Gaza Strip have violated the principle of proportionality ... and are to be seen as forms of collective punishment, which is forbidden," the Foreign Ministry.
It stressed there was "no doubt" that Israel had not taken the necessary precautions required of it under international law to protect the civilian population and infrastructure.
The destruction of a power station, supplying 43 percent of the Gaza Strip's electricity, the attack on the office of the Palestinian prime minister and the arbitrary arrests of large numbers of democratically elected legislators could not be justified, the ministry averred.
Israeli occupation forces have abducted a third of the Palestinian government, twenty four lawmakers and scores of municipal officials in nigh-time raids across the occupied West Bank last week.
Israel has threatened to topple the government, a warning made by Yuval Diskin, the head of Israel's Shin Beth domestic security agency, to President Mahmoud Abbas on Sunday, June 25.
The Palestinian government has denied any link to the operation and called on those holding the soldier to treat him well.
Osama al-Muzaini, a Hamas political leader, said the three resistance factions have withdrawn their representatives from the talks with the Egyptian mediators.
The groups are seeking the release of 1,000 prisoners in exchange for Shalit.
They had warned Israel that it will "bear full responsibility for future consequences" if their prisoner swap demands were not met.
The smallest of the three groups, the previously unknown Islamic Army, said there would be no further information released on 19-year-old Shalit.
They sent conflicting signals about his fate.
"Whether he will be killed or not killed, we will not disclose any information ... Discussion is closed," said Islamic Army spokesman Abu al-Muthana.
"We do not kill captives. Our Islam requires that we treat captives well and fairly."
He declined to say whether Shalit was alive or dead.
Muzaini compared the fate of Shalit to that of Israeli airman Ron Arad, who has been missing since bailing out of his plane over southern Lebanon 20 years ago.
There has been growing speculation Arad is dead.
"They may kill him, take him to another country or may hide him. All options are open."Güncelleme Tarihi: 20 Eylül 2018, 18:16