The United States on Saturday condemned the attacks by "Hamas terrorists" against Israel and vowed to ensure the key US ally has the means to defend itself.
President Joe Biden described the assault as "a terrible tragedy on a human level" and said he had spoken to Israeli Prime Minister Benjamin Netanyahu to underline his support.
"I told him the United States stands with the people of Israel in the face of these terrorist assaults," Biden said in a televised address from the White House.
"In my administration, support for Israel's security is rock solid and unwavering.
"We'll make sure that they have the help their citizens need and they can continue to defend themselves."
The statement came even as Netanyahu told his stunned nation that "We are at war," as the Israeli army retaliated by pounding targets in the blockaded enclave of Gaza, where several residential tower blocks were reduced to rubble.
About 80 people were killed in Israel, medical services said, while Gaza authorities released a death toll of 232 in the conflict's bloodiest escalation in years which also left many hundreds wounded on both sides.
"The enemy will pay an unprecedented price," Netanyahu vowed after Hamas had launched its first such combined ground, air and sea offensive, half a century after the outbreak of the 1973 Arab-Israeli war.
As the attacks threatened to trigger a wider conflict, Biden also warned "this is not a moment for any party hostile to Israel to exploit these attacks to seek advantage. The world is watching."
Biden stressed that Israel -- which the United States has supplied with billions of dollars of arms -- has "a right to defend itself and its people" after the Iran-backed Palestinian militant group Hamas launched air, sea and land strikes.
US Defense Secretary Lloyd Austin reaffirmed Washington's commitment, saying "over the coming days the Department of Defense will work to ensure that Israel has what it needs."
Trump weighs in
Former US president Donald Trump weighed in Saturday, blaming Biden, without evidence, for indirectly funding the attacks.
"These Hamas attacks are a disgrace and Israel has every right to defend itself with overwhelming force," Trump said in a statement.
"Sadly, American taxpayer dollars helped fund these attacks, which many reports are saying came from the Biden Administration."
Trump's allegations reflected Republican claims that $6 billion released last month to Iran as part of a prisoner exchange deal was used to fund the Hamas attack.
White House Deputy Press Secretary Andrew Bates said on social media that "this is a shameful lie in every respect, at a time when both parties should be totally united in supporting Israel's defense."
The money "can only be used for verifiable purchases of humanitarian needs like food and medicine," Bates added, in a fierce pushback against the claims.
Israel normalized relations decades ago with neighboring Egypt and Jordan and in 2020 added three more Arab states to the list -- the United Arab Emirates, Bahrain and Morocco -- in what Trump considered his towering foreign policy achievement.
The so-called "Abraham Accords" also included sweeteners from Trump, including a promise to sell jets to the United Arab Emirates.
"We brought so much peace to the Middle East through the Abraham Accords, only to see Biden whittle it away at a far more rapid pace than anyone thought possible," Trump, who plans to stand against Biden in the 2024 election, said.
Before Saturday's assault, Biden had been hoping to transform the Middle East -- and score a pre-election diplomatic victory -- by securing recognition of the Jewish state by Saudi Arabia, the guardian of Islam's two holiest sites.
Republican Senator Lindsey Graham said Saturday that "this unprecedented and brutal attack by Hamas is not only supported by Iran, it was designed to stop peace efforts between Saudi Arabia and Israel.
"A peace agreement between those two nations would be a nightmare for Iran and Hamas."
"It would serve Israel and the world well to respond to this outrage by launching an operation that will destroy the Hamas organization -- not just contain it," he added.
Hamas is backed by Iran, a fierce foe of Israel, with Iran's supreme leader declaring he was "proud" of Saturday's attacks.
Biden has had recently rocky relations with Netanyahu, publicly criticizing him for overhauling Israel's judiciary, a step seen by opponents as undermining democracy.
Netanyahu vows revenge
Israeli PM Netanyahu, meanwhile, warned Palestinians living near Hamas sites in Gaza to leave as he vowed to turn its hideouts into "rubble" following its surprise attack.
"All the places in which Hamas is based, in this city of evil, all the places Hamas is hiding in, acting from -- we'll turn them into rubble," he said.
"I'm telling the people of Gaza: get out of there now, because we're about to act everywhere with all our force," he said in a brief televised statement.
The latest conflagration erupted when dozens of Hamas fighters broke out of Gaza Strip and into nearby Israeli towns, killing many and abducting others in an unprecedented surprise early morning attack during a major Jewish holiday.
Netanyahu said the Israeli military will use all of its strength to destroy Hamas' capabilities. He also vowed to extract a heavy price if “even a single hair” is harmed on the Israeli hostages in Hamas captivity.
Israel has maintained a blockade over Gaza since Hamas seized control of the territory in 2007. The bitter enemies have fought four wars since then.
Jordanian king talks to Biden, warns against escalation
King Abdullah II of Jordan has called for intensifying international efforts to stop the escalation of the latest violence between the Palestinians and Israel.
A statement from the Royal Palace says Abdullah spoke to President Joe Biden about ways to to stop the conflict from escalating and ways to protect civilians.
Abdullah warned that continued escalation would have negative repercussions on the region and stressed the need for restraint, the protection of civilians and respect for international humanitarian law.
Hamas militants fired thousands of rockets and sent dozens of fighters into Israeli towns near the Gaza Strip in an unprecedented surprise early morning attack during a major Jewish holiday on Saturday.
It was the deadliest attack against Israel in decades.
Five things to know the multi-pronged attack by Hamas
Israel caught unawares
The shock that Israelis felt on Saturday morning -- on Simchat Torah, one of the most joyous days of the Jewish calendar -- recalled the surprise of the the 1973 Mideast war. Practically 50 years earlier to the day, a full-scale Egyptian-Syrian attack on a Jewish holiday quickly turned into a disaster for an unprepared Israeli military.
Then, as now, Israelis had assumed that their intelligence services would be able to alert the army to any major attack or invasion well in advance. That colossal failure still haunts the legacy of then-Prime Minister Golda Meir and helped bring down the lengthy rule of the once-dominant Labor Party.
Now, the question of how the militants were able to stage such a huge and coordinated attack -- which has already killed more Israelis than any single assault since the second Palestinian uprising two decades ago -- without triggering Israeli intelligence concerns has already presented a major challenge to Netanyahu’s ultranationalist government.
The government’s supporters had expected Netanyahu and hard-line ministers with a history of anti-Arab rhetoric like National Security Minister Itamar Ben-Gvir to take a particularly belligerent stance against the Palestinians and respond more forcefully to threats from militants in Gaza.
As political analysts lambast Netanyahu over the failure, and the casualty count climbs, Netanyahu risks losing control of both his government and the country.
Unprecedented infiltration
Hamas claimed its fighters took several Israelis captive in the enclave, releasing gruesome videos of militants dragging bloodied soldiers across the ground and standing over dead bodies, some of them stripped to their underwear. It said senior Israeli military officers were among the captives.
The videos could not immediately be verified but matched geographic features of the area. Fears that Israelis had been kidnapped evoked the 2006 capture of soldier Gilad Shalit, whom Hamas-linked militants seized in a cross-border raid. Hamas held Shalit for five years until he was exchanged for over 1,000 Palestinian prisoners held by Israel.
In a dramatic escalation unseen in decades, Hamas also sent paragliders flying into Israel, the Israeli military said. The brazen attack recalled a famous assault in the late 1980s when Palestinian militants crossed from Lebanon into northern Israel on hang-gliders and killed six Israeli soldiers.
The Israeli army belatedly confirmed that soldiers and civilians were taken hostage in Gaza, but refused to provide further details.
A dangerous gamble by Hamas
Hamas officials cited long-simmering sources of tension between Israel and the Palestinians, including the dispute around the sensitive Al-Aqsa Mosque compound, which is is sacred to both Muslims and Jews and remains at the emotional heart of the Israeli-Palestinian conflict. Competing claims over the site, known to Jews as the Temple Mount, have spilled into violence before, including a bloody 11-day war between Israel and Hamas in 2021.
In recent years, Israeli religious nationalists -- such as Ben-Gvir, the national security minister -- have increased their visits to the compound. Last week, during the Jewish harvest festival of Sukkot, hundreds of ultra-Orthodox Jews and Israeli activists visited the site, prompting condemnation from Hamas and accusations that Jews were praying there in violation of the status quo agreement.
Hamas statements have also cited the expansion of Jewish settlements on lands that the Palestinians claim for a future state and Ben-Gvir’s efforts to toughen restrictions on Palestinian prisoners in Israeli jails.
More recently, tensions have escalated with violent Palestinian protests along the Gaza frontier. In negotiations with Qatar, Egypt and the United Nations, Hamas has pushed for Israeli concessions that could loosen the 17-year blockade on the enclave and help halt a worsening financial crisis that has sharpened public criticism of its rule.
Some political analysts have linked Hamas’ attack to current U.S.-brokered talks on normalization of ties between Israel and Saudi Arabia. So far, reports of possible concessions to Palestinians in the negotiations have involved Palestinians in the occupied West Bank, not Gaza.
“We have always said that normalization will not achieve security, stability, or calm,” Bassem Naim, a senior Hamas official, told the Associated Press.
Israel in crisis
The eruption of violence comes at a difficult time for Israel, which is facing the biggest protests in its history over Netanyahu’s proposal to weaken the Supreme Court while he is on trial for corruption.
The protest movement, which accuses Netanyahu of making a power grab, has bitterly divided Israeli society and unleashed turmoil within the Israeli military. Hundreds of reservists have threatened to stop volunteering to report for duty in protest at the judicial overhaul.
Reservists are the backbone of the country’s army, and protests within the army ranks have raised concerns about the military’s cohesion, operational readiness and power of deterrence as it confronts threats on multiple fronts. Netanyahu on Saturday called up “an extensive mobilization of reserve forces.”
A perilous cycle
Israel and Hamas have fought four wars and exchanged fire numerous times since the Islamic militant group seized control of Gaza from forces loyal to the Palestinian Authority in 2007. Cease-fires have stopped major fighting in past rounds of conflict but have always proven shaky.
Each agreement in the past has offered a period of calm, but the deeper, underlying issues of the conflict are rarely addressed and set the stage for the next round of airstrikes and rockets.
With its increased leverage in this round, Hamas is likely to push harder for concessions on key issues, such as easing the blockade and winning the release of prisoners held by Israel.
(With inputs from AP, AFP)