Israeli artillery pounded the northern Gaza Strip today as troops and tanks prepared to widen an offensive designed to force Palestinian militants to release an abducted soldier.
Israel also turned up the heat on Syria, sending warplanes low over one of President Bashar al-Assad's palaces to warn him against backing militants who kidnapped the soldier.
Mr Bashar was in the palace at the time, Israeli media said.
Threatening what he called extreme steps if Corporal Galid Shalit was not freed, Israeli Prime Minister Ehud Olmert said a large-scale operation that began with a push into southern Gaza earlier today would continue "over the coming days".
A Defence Ministry source said Mr Olmert had given approval for forces massed opposite northern Gaza to also push across the border. No timeframe was given but Israeli media said leaflets would soon be dropped warning Palestinians of imminent attack.
Israeli shells were landing every couple of minutes in open areas of northern Gaza, witnesses said.
There have as yet been no clashes with masked gunmen waiting behind barricades and in alleyways for battle to begin.
Foreign powers trying to revive Israel-Palestinian peace talks expressed dismay at the surge in tensions, demanding militants free Cpl Shalit while urging Israel to show restraint.
The ground offensive is Israel's first into Gaza since it quit the territory last year after 38 years of occupation.
Gunmen seized Cpl Shalit in a cross-border raid on an army post on Sunday. In a statement, the ruling Hamas movement defended the kidnapping but did not claim any role in the kidnapping.
Earlier, Israeli troops backed by assault helicopters and artillery set up a strategic observation post at a disused airport outside the southern town of Rafah. Aircraft also attacked Gaza's only power plant, cutting off electricity to much of the impoverished coastal territory, where 1.4 million Palestinians live.
Palestinian President Mahmoud Abbas called the bombardment of civilian infrastructure "a crime against humanity".
Mr Olmert said Israel had "no intention of recapturing" the Gaza Strip. "We have a central goal and that is to bring Gilad home," he said in a speech in Jerusalem.
In another challenge to Israel, militants threatened to kill an 18-year-old Jewish settler they said they had seized in the West Bank today.
Israeli authorities said the settler had been missing since Sunday but have not confirmed he was abducted.
Another militant group said it had seized another settler in the occupied West Bank. Police said a 62-year-old man was missing but did not know if he had been kidnapped.