Israel's war on Hamas will last for months, Israel's military chief said on Tuesday while the United Nations voiced alarm over an escalation of Israeli attacks that killed more than 100 Palestinians over two days in part of the Gaza Strip.
Israel's Chief of Staff Herzi Halevi told reporters in a televised statement on the Gaza border that the war would go on "for many months".
"There are no magic solutions, there are no shortcuts in dismantling a terrorist organization, only determined and persistent fighting," Halevi said.
"We will reach Hamas' leadership too, whether it takes a week or if it takes months."
Israeli actions , particularly in a central area just south of the seasonal waterway that bisects the Gaza Strip.
The Israeli army told civilians to leave the area, though many said there was no safe place left to go.
"We are gravely concerned about the continued bombardment of Middle Gaza by Israeli forces, which has claimed more than 100 Palestinian lives since Christmas Eve," said UN Human Rights Office spokesperson Seif Magango.
"Israeli forces must take all measures available to protect civilians.
"Warnings and evacuation orders do not absolve them of the full range of their international humanitarian law obligations."
On Tuesday, the US said Sigrid Kaag, the outgoing Dutch finance minister, would be the coordinator for humanitarian relief shipments into Gaza as part of a UN Security Council resolution adopted on Friday.
Israel is determined to destroy Hamas despite growing international calls for a ceasefire in the 11-week-old war and new concerns the conflict could spread, with US and Iran-aligned forces attacking each other elsewhere in the region.
The war is the latest escalation in a long-standing conflict.
Since Hamas killed 1,200 people and captured 240 hostages on 7 October in the deadliest day in Israeli history, Israeli Prime Minister Benjamin Netanyahu has responded with an assault that has laid much of Hamas-ruled Gaza to waste.
Palestinian health authorities said nearly 21,000 people had been killed in Israeli strikes, with thousands more feared buried under rubble.
Nearly all of the enclave's 2.3 million people have been driven from their homes, many several times.
Israel says it is doing what it can to protect civilians, and blames Hamas for putting them in harm's way by operating among them, which Hamas denies.
But even Israel's closest ally the United States has said it should do more to reduce civilian deaths from what President Joe Biden has called "indiscriminate bombing".
Hamas is a Palestinian political and military group, which has governed the Gaza Strip since the most recent elections in 2006.
Hamas' stated aim is to establish a Palestinian state and stop the Israeli occupation of Gaza and the West Bank, illegal under international law.
Hamas in its entirety is listed as a terrorist organisation by the European Union and seven other countries, including Australia. But the UN Assembly rejected classifying Hamas as a terrorist group in a 2018 vote.
In 2021 the International Criminal Court opened an investigation into alleged Israeli war crimes in the Palestinian territories dating back to 2014, including the recent attacks of both Israel and Hamas.
Israeli minister in Washington
In Washington, Israeli Minister of Strategic Affairs Ron Dermer was due to meet US Secretary of State Antony Blinken and national security adviser Jake Sullivan on Tuesday for talks on the war and the return of hostages, the White House said.
Washington has openly pressed Israel in recent weeks to scale down its war from a full-blown military assault to a more targeted operation of raids on Hamas leaders.
Israel says it will not stop fighting until Hamas is completely destroyed.
Netanyahu adviser Mark Regev told CNN on Tuesday that destroying Hamas, which has ruled Gaza since 2007, was "a prerequisite for a better future both for Israelis and Palestinians".
"You won't have a demilitarised and deradicalised Gaza without first destroying Hamas. You can't have reconstruction in Gaza, rebuilding the lives of people without first getting rid of Hamas."
In a further sign of regional volatility, Yemen's Iran-backed Houthi militia said it had fired a drone toward Eilat, southern Israel, but the Israeli military said one of its fighter jets intercepted what it called the "hostile aerial target" in the Red Sea area before it could reach Israel.
The Houthis they say have links to Israel in the entrance to the Red Sea, one of the world's busiest shipping lanes.
US forces, meanwhile, have come under attack by Iran-backed militants in Iraq and Syria over Washington's backing of Israel.
The US military carried out retaliatory airstrikes on Monday in Iraq after a drone attack by Iran-aligned militants on a US base in Erbil left one US service member in critical condition and wounded two.
The airstrikes killed "a number of Kataib Hezbollah militants" and destroyed multiple facilities used by the group, the US military said.
On Monday an Israeli airstrike killed a senior leader of Iran's Revolutionary Guards in Syria.
And on the Lebanon border on Tuesday, Israel said that Hezbollah fired anti-tank missiles at a church, wounding a civilian and nine Israeli soldiers, after which it fired rockets from near a mosque, drawing retaliatory airstrikes.
"We are in a multi-front war and are coming under attack from seven theatres: Gaza, Lebanon, Syria, Judea and Samaria (the West Bank), Iraq, Yemen and Iran," Israeli Defence Minister Yoav Gallant told lawmakers, listing six places where Iran-backed militants are active, as well as Iran itself.
"We have already responded and taken action in six of these theatres," he said, without specifying the one that had yet to see Israeli action.
In India, there was an explosion near the Israeli embassy in New Delhi.
Authorities said no staff were hurt.