WASHINGTON - US President Joe Biden will visit Israel Wednesday in a show of "ironclad" support as Washington tries to prevent the escalating war against Hamas in Gaza from spilling into a wider Middle East conflict.
Anger and bloodshed have surged as the war has claimed thousands of lives since the Islamist attack, with most of the dead on both sides civilians.
Biden's trip will come 12 days after the Palestinian militants of Hamas burst through Israel's heavily fortified Gaza border, killing, mutilating and burning more than 1,400 people.
Shell-shocked Israel has responded with withering air strikes that have killed more than 2,700 people. It has also imposed a crippling siege on Gaza and deployed tens of thousands of troops in preparation for a full-scale ground offensive.
Israel has vowed to destroy Hamas while also seeking to rescue the at least 199 hostages taken into Gaza by Hamas, which has released a video of one of the captives, French-Israeli woman Mia Shem.
Her mother, Keren Shem, made an emotional plea for her safe return, at a Tel Aviv press conference.
"I ask world leaders that my daughter be returned to us in the state that she is today, as well as the other hostages," she said.
"I am begging the world to bring my baby back home."
- Iran warning -
Army spokesman Jonathan Conricus said Tuesday that Israeli forces "will commence the enhanced military activities when the timing suits the goal".
He stressed that "if hostages are dead, that is the responsibility of Hamas and Hamas will pay the price", with the army later announcing the killing of a senior Hamas commander, Ayman Nofal.
Israelis are still reeling from the worst attack in the country's 75-year history, which has sparked a mass mobilisation of reservists and the evacuation of about 500,000 people from areas near Gaza and Lebanon.
US Secretary of State Antony Blinken, back in Israel after a whistlestop regional tour, said Biden's visit would be a statement of "solidarity with Israel" and an "ironclad commitment to its security".
Washington has already sent two aircraft carrier strike groups to the eastern Mediterranean "to deter hostile actions against Israel".
The Pentagon has put 2,000 troops on deployment alert to be able "to respond quickly to the evolving security environment in the Middle East". US media said the troops would cover support roles such as medical assistance and handling explosives.
Iran's supreme leader Ayatollah Ali Khamenei said Tuesday that "no one can stop" forces opposed to Israel if it keeps up its bombardment of Gaza.
Deadly flare-ups have rocked Israel's northern border with Lebanon, where the Iran-backed Hezbollah movement is based.
Israel's army said Tuesday it had killed four militants attempting to infiltrate from Lebanon, the latest in a series of incidents.
White House National Security Council spokesman John Kirby was asked on CNN whether US authorities had so far noticed Iran engaging in the conflict in new ways.
"Outside of the rhetoric..., no we haven't," he replied.
- 'Corpses in the streets' -
While signalling support, Biden will also try to quietly steer Israeli's military response, as international alarm has grown about the devastating impact of the war on Palestinian civilians.
At least 2,750 Palestinians -- mostly civilians -- have been killed, entire neighbourhoods have been razed and survivors are left with dwindling supplies of food, water and fuel.
"The situation is catastrophic beyond what I could have imagined," said Jamil Abdullah, a Palestinian-Swede, hoping to flee the blockaded enclave.
"There are corpses in the streets. Buildings are crashing down on their inhabitants. Blood is everywhere. The smell of the dead is everywhere."
AFP reporters in Gaza said mortuaries were overflowing, and corpses wrapped in white body bags were even being stored in an ice cream truck.
"Enough!" cried Moamed Abu Zaid, counting about 20 family members killed in one strike. "How long will this continue for?"
The UN agency for Palestinian refugees says more than one million Palestinians -- almost half of Gaza's population of 2.4 million -- have fled their homes.
World Health Organization regional director Ahmed Al-Mandhari told AFP that Gaza was barrelling towards "real catastrophe".
Israel has demanded that residents of north Gaza leave for the south, hoping to clear the area of civilians in preparation for a ground assault that would involve gruelling urban combat.
- No escape -
Since Israel's evacuation order in north Gaza, entire families, young children and the elderly have gathered belongings and fled to southern Gaza, bedding down in any available space, indoors and out.
Egypt kept closed Gaza's only border crossing not controlled by Israel, Rafah, meaning there is no escape.
Israel has repeatedly struck the area on the Palestinian side and denied reports of any temporary ceasefire deal to open it.
Rafah's closure has so far prevented the escape of thousands of Palestinian-Americans and others hoping to get out of Gaza, or the entry of relief goods now loaded on truck convoys waiting in Egypt.
For now Gazans remain trapped, with neighbouring Arab nations also fearful that if Palestinians leave the territory they could be permanently exiled.
Blinken, after talks with Israeli Prime Minister Benjamin Netanyahu, signalled there was no agreement yet on humanitarian relief, but said there was a "commitment" to work on a plan ahead of and during Biden's visit.
Blinken said the US president hopes to "hear from Israel how it will conduct its operations in a way that minimises civilian casualties and enables humanitarian assistance to flow to civilians in Gaza in a way that does not benefit Hamas."
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By Daphne Rousseau With Adel Zaanoun In The Gaza Strip