CAIRO/GAZA/JERUSALEM, Dec 15 (Reuters) - A U.S. security envoy had talks with Israel about shifting its strategy in Gaza toward surgical operations against Hamas from a broad ground campaign, and President Joe Biden appealed for civilian lives in the Palestinian territory to be saved.

With nightfall on Thursday, Israeli tanks and planes intensified bombardment of the northern Gaza neighbourhoods of Shejaia, Zeitoun and Daraj as well as Khan Younis in the south of the enclave, residents said. Four people, including two children, were killed and several others wounded in an Israeli air strike on a house in Khan Younis in southern Gaza early on Friday, Palestinian health officials said.

Israel has been pounding the 25-mile (40-kilometer) length of Gaza with no sign of a pause in hostilities or a ceasefire that would enable delivery of more desperately needed basic supplies for civilians to survive as their homes have been destroyed.

Israel launched its military campaign in Gaza in retaliation for a rampage by Hamas, the Iran-backed group that rules Gaza, whose fighters killed 1,200 Israelis and seized 240 hostages in a cross-border raid on Oct. 7.

Israeli forces have besieged the coastal strip and laid much of it to waste, with nearly 19,000 people confirmed dead, according to Palestinian health officials, and thousands more feared buried under the rubble.

White House national security adviser Jake Sullivan discussed moves on Thursday to shift Israel's attacks on Gaza to lower-intensity operations focused on high-value targets during his visit to Israel, but it would be "irresponsible" to give specific time frames for such a change, a senior administration official told reporters.

"There was a discussion in these meetings and also in our prior meetings, and in calls between the President and the Prime Minister, on kind of a shift in emphasis from high-tempo clearance operations, high intensity clearance operations, which are ongoing now, to ultimately lower intensity focus on high-value targets, intelligence driven raids, and those sorts of more narrow, surgical military objectives," said the official, who asked not to be identified.

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