The assault raised risks of a bloodier conflict amid escalating Palestinian civilian casualties and the first Israeli military death — and brought questions of how far Israel will go to cripple Gaza's Hamas rulers.
Officially, the goal remains to destroy a network of tunnels militants use to infiltrate Israel and attack civilians. In its first day on the ground in Gaza, the military said it took up positions beyond the border, encountered little resistance from Hamas fighters and made steady progress in destroying the tunnels. Military officials said the quick work means that within a day or two, Israeli leaders may already have to decide whether to expand the operation. More pics after cut

With calls from Israeli hard-liners to completely crush Hamas, it remains unclear how far Israel will go in an operation that has already seen 299 Palestinians killed in 11 days of intense Israeli bombardment of the densely populated coastal strip, a fifth of them children.
Palestinians salvage their usable belongings from the rubble of their homes in an apartment building after it was hit by an Israeli missile strike in Gaza City, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers. (AP Photo/Hatem Moussa)
Palestinian mourners gather around the bodies of three siblings of the Abu Musallam family, during their funeral in Beit Lahiya, northern Gaza Strip, Friday, July 18, 2014. Ismail Abu Musallam, the father of the children said that Ahmed, 11, Walaa, 14 and Mohammed,16, were sleeping when the shell struck the family home, and that he had to dig them out of the rubble. (AP Photo/Lefteris Pitarakis)
A Palestinian man stands in the rubble of a house after it was hit by an Israeli missile strike in Gaza City, Friday, July 18, 2014. Israel intensified its 11-day campaign against Hamas by sending in tanks and troops late Thursday after becoming increasingly exasperated with unrelenting rocket fire from Gaza on its cities, especially following Hamas' rejection of an Egyptian cease-fire plan earlier in the week.(AP Photo/Hatem Moussa)
Smoke rises after an Israeli missile strike in Gaza City, Friday, July 18, 2014. Israel intensified its 11-day campaign against Hamas by sending in tanks and troops late Thursday after becoming increasingly exasperated with unrelenting rocket fire from Gaza on its cities, especially following Hamas' rejection of an Egyptian cease-fire plan earlier in the week.(AP Photo/Hatem Moussa)
Smoke rises behind a mosque's minarets after an Israeli missile strike in Gaza City, northern Gaza Strip, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers. (AP Photo/Hatem Moussa)
Palestinians inspect the rubble of a building to pick up their usable belongings after it was hit by an Israeli missile strike in Gaza City, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers. (AP Photo/Hatem Moussa)
A Palestinian man burns a tire during clashes with Israeli soldiers following a protest against the Israeli offensive in Gaza, outside Ofer, an Israeli military prison near the West Bank city of Ramallah, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave’s Hamas rulers. (AP Photo/Majdi Mohammed)
An Israeli border policeman aims his weapon during clashes with Palestinians following a protest against the Israeli offensive in Gaza, outside Ofer, an Israeli military prison near the West Bank city of Ramallah, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave’s Hamas rulers. (AP Photo/Majdi Mohammed)
Protesters chant slogans against Israel to condemn its bombing on Gaza and to demand Hamas and other Palestinian brigades in Gaza reject any truce with Israel, during a protest by followers of the Muslim Brotherhood in Amman, Jordan, Friday, July 18, 2014. The Arabic writing reads, "The Arab regimes are Zionists." Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers. (AP Photo/Mohammad Hannon)
Smoke from flares rises in the sky in Gaza City, in the northern Gaza Strip, Thursday, July 17, 2014. Israel launched a large-scale ground offensive in the Gaza Strip Thursday, escalating a 10-day military operation to try to destroy Hamas' weapons arsenal, rocket firing abilities and tunnels under the Palestinian territory's border with Israel. It was the first major Israeli ground offensive in Gaza in just over five years. (AP Photo/Lefteris Pitarakis)
An Israeli soldier walks with a prayer shawl near the border of Israel and Gaza, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers. Israel launched the operation late Thursday, following a 10-day campaign of more than 2,000 air strikes against Gaza that had failed to halt relentless Hamas rocket fire on Israeli cities. (AP Photo/Tsafrir Abayov)
Palestinians inspect the rubble of a house after it was hit by an Israeli missile strike in Gaza City, Friday, July 18, 2014. Israeli troops pushed deeper into Gaza on Friday to destroy rocket launching sites and tunnels, firing volleys of tank shells and clashing with Palestinian fighters in a high-stakes ground offensive meant to weaken the enclave's Hamas rulers.(AP Photo/Hatem Moussa)