The operation comes after ten days of intense fighting between Israel and the Islamic militant Hamas, in which Israel hit more than 2,000 targets in Gaza and Hamas launched nearly 1,500 rockets at Israel.
The army said the offensive is meant to strike a “significant blow to Hamas’ terror infrastructure.”
It did not say how many troops were involved or provide other details.
Israeli prime minister Benjamin Netanyahu’s office said he instructed the army to go ahead after Hamas rejected an Egyptian ceasefire plan earlier in the week and after Hamas militants tried to infiltrate into Israel through a tunnel from Gaza earlier on Thursday.
“In light of the despicable and relentless aggression by Hamas and the dangerous infiltration into Israel, Israel is obliged to protect its citizens,” the statement said.
Palestinian militants also fired a rocket at Israel during the day, just as a five-hour UN humanitarian ceasefire expired, the
Israeli military said.
Gaza residents had crowded banks, vegetable markets and shops as they took advantage of the first respite from ten days of fierce fighting. The military said the rocket struck the city of Ashkelon at precisely 3pm as the pause in military activity ended.
No injuries were reported. Gaza militants also fired three mortar shells toward Israel after the truce took effect at 10am. Israel has not responded yet to either incident.
Gaza City – a virtual ghost town for the past ten days – returned to apparent normality within minutes of the start of the truce. Large crowds formed outside banks, with people jostling and shouting to get to cash machines. In an outdoor market, shoppers filled plastic bags with fruit, vegetables and freshly slaughtered chickens.
The rush to restock signalled that Gaza residents do not expect a quick end to the fighting.
Egypt renewed ceasefire efforts after its initial attempt collapsed earlier in the week, but the demands of Israel and Hamas remain far apart.
“The situation is likely to get worse because there is no clear way out of it,” said Moussa Amran, 43, a money-changer in central Gaza City.
Israel accepted Egypt’s initial call earlier this week to halt all hostilities, but Hamas rejected the idea because it does not want to return to the situation before the outbreak of fighting.
An intensified Egyptian border blockade of Gaza over the past year, combined with long-running Israeli restrictions on access, had severely weakened the Islamic militant group.
Egypt’s foreign minister Sameh Shukri insisted that the ceasefire deal was still alive and expressed frustration that “Palestinian factions” – a clear reference to Hamas – had not agreed to it.
Hamas’ agreement is crucial to any such truce, but its demand that the blockade be eased significantly is likely to be rejected by Israel and Egypt because it would strengthen the group’s hold on Gaza, where it seized power in 2007.
Thursday’s temporary truce, brokered by the UN, came after Israel carried out nearly 2,000 air strikes on Gaza over ten days and Hamas fired more than 1,300 rockets into Israel, reaching the country’s economic and cultural heartland. The cross-border fighting has so far killed more than 230 Palestinians and an Israeli, according to officials.
Also on Thursday, a Jerusalem court indicted a 29-year-old and two 16-year-olds over the death of Mohammed Abu Khdeir, 16, after he was kidnapped.