Israeli warplanes launched fierce air raids on Gaza before dawn on Monday as Palestine's Hamas continued firing rockets targeting Israeli towns – extending the deadly conflicts into a second week.
Israel's Prime Minister Benjamin Netanyahu said the operation would "take time". During a television appearance, he said, "We will do whatever it takes to restore order and quiet."
Hours after the announcement, explosions shook Gaza City from north to south in a bombardment that was heavier, wider, and lasted longer than Sunday's air raids, which killed at least 42 Palestinians and injured dozens more, reported Qatar-based TV channel Al Jazeera.
At least 198 people, including 58 children, have been killed in the Gaza Strip since the latest violence began a week ago. More than 1,300 Palestinians were also wounded. Israel has reported 10 dead, including two children, said the television channel.
In the latest assaults, the Israeli military said it had been targeting the network of tunnels used by militants that runs beneath.
The Israeli army said 54 Israeli warplanes took part in the attack using 110 rockets and bombs as they attacked around 35 targets for a period of 20 minutes, reported multiple international news agencies.
During the operation, the army said, a tunnel route around 50 feet long was destroyed. Warplanes also targeted the homes of Hamas's military leaders, the Israeli military said.
Representatives from the US, Qatar, Egypt, and other countries have been attempting to mediate a cease-fire. But their efforts so far have been futile.
US Secretary of State Antony Blinken at a news conference in Denmark said the US remains greatly concerned over the escalating violence and is working "extensively" behind the scene to bring hostilities to an end.
The US diplomat urged all parties to ensure the protection of civilians and repeated that Israel has an extra burden to do everything in order to avoid civilian casualties.
Before the media brief, Qatari, Egyptian and Saudi foreign ministers had spoken with the top US envoy over phone on deadly Israeli air attacks.
Turkish President Recep Tayyip Erdogan urged Pope Francis to help end what he called Israel's "massacre" of Palestinians, which should be punished with sanctions, his office said.
On Monday, Israeli diplomat Mark Regev – who is also a senior advisor to Israeli Prime Minister Benjamin Netanyahu – told the BBC that Israel does not "want to see this end in a way that we are just back to square one a month from now".
"A premature cessation of hostilities, which gives Hamas a victory – that is not going to help anyone. If Hamas comes out of this empowered, that is bad for Israel, that's bad for Palestinians, that is bad for peace," he commented.
Meanwhile, the Washington Post reported that US President Joe Biden has approved a $735 million sale of precision-guided weapons to Israel. According to the paper, Congress was officially notified of the proposed sale on 5 May – almost a week before the current violence began.
Some of Biden's fellow Democrats are now criticising the sale, the paper reports.
One Democrat on the House Foreign Affairs Committee told the paper that "allowing this proposed sale of smart bombs to go through without putting pressure on Israel to agree to a ceasefire will only enable further carnage".
In another development, the Reporters Without Borders and Amnesty International asked the International Criminal Court to investigate Israel's bombing of a building housing media outlets including Al Jazeera and the Associated Press, as a possible war crime.
The Doctors Without Borders said the heavy bombardment of Gaza over the past week has been catastrophic as roads, water, sanitation and other infrastructure have been damaged, putting extreme pressure on the territory's already fragile health system.
Palestinian Prime Minister Mohammad Shtayyeh urged countries to offer more concrete action, rather than words, against Israel, reported Al Jazeera.
"Frankly speaking it's not enough at all to have declarations," said Shtayyeh, speaking from the city of Ramallah in the occupied West Bank.
"The UN must issue a resolution that describes all these actions as illegal and illegitimate against the Palestinian people," he said, calling for sanctions against Israel.
Shtayyeh also urged allies to summon ambassadors of Israel, to halt trade relations with the country and stop aid coming from the US and the European Union "until Israel respects human rights".
The fighting between Israel and Hamas was triggered by days of escalating clashes between Palestinians and Israeli police at a holy hilltop compound in East Jerusalem.
The site is revered by both Muslims, who call it the Haram al-Sharif (Noble Sanctuary), and Jews, for whom it is known as the Temple Mount. Hamas demanded Israel remove police from there and the nearby predominantly Arab district of Sheikh Jarrah, where Palestinian families face eviction by Jewish settlers. Hamas launched rockets when its ultimatum went unheeded.
Palestinian anger had already been stoked by weeks of rising tension in East Jerusalem, inflamed by a series of confrontations with police since the start of the Islamic holy month of Ramadan in mid-April.