The region was in limbo. There were hopes for a measured and targeted response, but there were also preparations for a large-scale attack. Diplomats warned that this could lead to a regional war.

Beirut residents stocked up on emergency supplies in case the expected attacks reached the Lebanese capital. Hezbollah militants threatened to attack Haifa and other Israeli cities if they did. Turkish President Recep Tayyip Erdogan told his supporters that Turkey could “invade” Israel if necessary, prompting a rebuke from Israel.

During a visit to the Israeli-occupied Golan Heights, the site of Saturday’s deadly attack, Israeli Prime Minister Benjamin Netanyahu said Monday that Israel “will not and cannot ignore this,” before vowing to strike back. “Our response will come, and it will be severe.”

Israeli Finance Minister Bezalel Smotrich said Monday that “there is no way to restore the security of the residents of the north without a war that will destroy Hezbollah, retake southern Lebanon and return the security zone that is currently on our territory to Lebanon.”

The comments came after Israel’s security cabinet gave Netanyahu and his defense minister permission Sunday night to decide on the “manner and timing” of Israel’s response to Saturday’s rocket attack. The Israel Defense Forces on Sunday released a list of victims ranging in age from 10 to 16.

“There are huge concerns that things could get out of hand,” said an Israeli official, who spoke on condition of anonymity because he was not authorized to speak publicly.

“For me, a Jewish child killed … on October 7 or a Druze child killed in the Golan Heights is the same,” Israeli Defense Minister Yoav Gallant said Monday during a visit to the village of Majdal Shams, where the attack took place. “Hezbollah will pay a price for this — our actions will speak.”

Gallant spoke to U.S. Defense Secretary Lloyd Austin on Monday by phone, in which he told Austin that the use of an Iranian missile equipped with 50 kilograms (110 pounds) of explosives indicated Hezbollah’s responsibility for the attack. Hezbollah, which is backed by Iran, has denied any connection to the attack.

The Israeli army on Sunday struck a number of Hezbollah targets deep inside Lebanon. Hussein Fakih, a spokesman for the Lebanese Civil Defense, said in an interview that two people were killed and three, including a child, were wounded in an attack on Monday on the road between Chaqra and Meiss El Jabal, in southeastern Lebanon. Later on Monday, Hezbollah announced the deaths of two of its members.

About 20 projectiles fired from southern Lebanon fell in an open area in northern Israel, the IDF said Monday, adding that it destroyed the launcher used in Lebanon. No injuries were reported.

A flurry of diplomatic efforts to calm the situation, launched from Washington, Paris and regional capitals, began within hours of the attack, according to Western and Israeli officials familiar with the situation. U.S. officials said Israel had the right to respond to the attack but also urged its ally to show restraint.

Early signs suggested that Jerusalem might be listening. The Yedioth Ahronoth newspaper quoted anonymous Israeli officials as describing the likely operation as “limited but significant.”

Israel’s dilemma, according to current and former security officials, is how to respond to the attack without leaving Hezbollah no choice but to escalate — which could draw Iran more directly into the fight. The Israeli military maintains a series of targeting scenarios, updated regularly with new intelligence, according to a military official who described the preparedness planning to The Washington Post during a visit to the border zone in the spring.

Planners will also look at recent responses. This month, after a drone strike by Iran-backed Houthi rebels in Yemen killed one person in Tel Aviv, Israel responded a day later with a devastating strike that severely damaged a major Yemeni port.

In April, after Israel and its allies shot down the bulk of an unprecedented barrage of missiles and drones from Iran, the military responded with a calibrated counterattack that showed it could reach Iranian territory but caused minimal damage. Both sides withdrew.

Some major airlines are suspending and rescheduling their flights to Beirut, citing tensions in the Middle East. Air France said Monday that flights between Paris Charles de Gaulle Airport and Beirut would be suspended on Monday and Tuesday, while German carrier Lufthansa said it was suspending flights to Beirut through August 5. Lebanon’s main carrier, Middle East Airlines, rescheduled flights to and from Beirut on Sunday and Monday, citing “technical reasons related to the distribution of insurance risks.”

US Secretary of State Antony Blinken expressed his condolences to the victims of the Majdal Shams attack in a phone call with Israeli President Isaac Herzog on Monday, in addition to stressing “the importance of preventing escalation of the conflict,” Foreign Office spokesman Matthew Miller said. British Foreign Secretary David Lammy said on social media that he had spoken to Lebanese Prime Minister Najib Mikati about the escalating tensions, with both agreeing that “expanding the conflict in the region is not in anyone’s interest.”

Hamas accused Netanyahu on Monday of delaying ceasefire negotiations by “setting new conditions and demands.” In response, Netanyahu said it was Hamas that “prevented an agreement” by demanding changes, and that Israel “has neither changed the contours nor added conditions to them.” Both Israel and Hamas are under pressure to close the remaining gaps in reaching an agreement to at least temporarily end more than nine months of conflict.

Far-right protesters gathered outside and broke into the Sde Teiman military base in Israel after nine reservists were detained on charges of “severe mistreatment of a prisoner.” Some politicians, including members of Netanyahu’s cabinet, issued statements supporting the protesters’ cause. Netanyahu himself, as well as the IDF leadership and Herzog, condemned the break-in and called for calm to be restored.

According to human rights groups, conditions in Israeli prisons have deteriorated dangerously since October 7, as detailed in a Post report . The Post spoke to former Palestinian prisoners and lawyers and reviewed autopsy reports and court records to reveal widespread violence and deprivation in the Israeli prison system, with routine beatings — usually with batons — and occasional dog attacks, as well as psychological abuse and denial of adequate food and medical care.

At least 39,363 people have been killed and 90,923 wounded in Gaza since the war beganaccording to the Gaza Health Ministry, which makes no distinction between civilians and fighters but says the majority of the dead are women and children. Israel estimates that about 1,200 people were killed in the Hamas attack on Israel on October 7, including more than 300 soldiers, and says 329 soldiers have been killed since the start of the military operation in Gaza.

Kareem Fahim and Suzan Haidamous in Beirut, Lior Soroka in Tel Aviv and Michael Birnbaum in Tokyo contributed to this report.