Diplomatic pressure mounted Monday to avoid an escalation between Iran and Israel following high-profile killings that have sent regional tensions soaring, while numerous governments urged their citizens to leave Lebanon.
Israeli Prime Minister Benjamin Netanyahu said late Sunday that his country was "determined to stand against" Iran and its allied armed groups "on all fronts."
As its war against Iran-backed Hamas in Gaza nears its 11th month, Israel has been bracing for retaliation from the Tehran-aligned "axis of resistance" for the assassinations of two senior terrorist figures.
Palestinian armed group Hamas' political leader, Ismail Haniyeh, was killed in Tehran on Wednesday in an attack blamed on Israel, which has not directly commented on it.
The killing came hours after an Israeli strike on Beirut left Hezbollah military chief Fuad Shukr dead.
Tehran said Monday that "no one has the right to doubt Iran's legal right to punish the Zionist regime" for Haniyeh's killing.
U.S. Secretary of State Antony Blinken told his counterparts from the G7 nations in a conference call Sunday that any attack, which he expected to be a joint undertaking between Hezbollah and Iran, could happen within 24 to 48 hours, as early as Monday, Axios reported.
Blinken asked his counterparts to place diplomatic pressure on Tehran, Hezbollah and Israel to "maintain maximum restraint," it added.
Israel's military spokesman Daniel Hagari on Sunday said that "as of now there is no change" in its policy for protecting civilians.
In the northern port city of Haifa, shop owner Yehuda Levi, 45, told Agence France Presse that Israelis are used to conflict, but facing a multipronged attack "is a little tricky."
"It's difficult, but we believe we're a strong country," he said. "We're going to win this war."
Experts and diplomats fear that the expected attack on Israel could rapidly spiral into a regional war.
Turkey on Monday joined multiple Western and other nations calling on their citizens to leave Lebanon, where Hezbollah is based.
Numerous airlines have suspended flights to the country or limited them to daylight hours.
Germany's Lufthansa, which has already suspended flights to the region, including Tel Aviv, said its planes would avoid Iraqi and Iranian airspace until at least Wednesday.
The United Nations' rights chief, Volker Turk, called on "all parties, along with those states with influence, to act urgently to de-escalate what has become a very precarious situation."
Italian Foreign Minister Antonio Tajani, whose country holds the rotating G7 presidency, said in a statement: "We call on the parties involved to desist from any initiative that could hinder the path of dialogue and moderation."
On Sunday, Jordan's Foreign Minister Ayman Safadi made a rare trip to the Iranian capital during which he delivered a message from King Abdullah II to President Masoud Pezeshkian.
Jordanian "airspace will probably be a theater for missiles and anti-missile" fire in any direct Iranian-Israeli clashes, but Amman would strongly object to violations of its sovereignty, said political analyst Oraib Rantawi.
"The Iranians must find other ways to spare Jordan this embarrassment," Rantawi, director of the Amman-based Al Quds Center for Political Studies, told AFP.
The Israel-Hamas war in the Gaza Strip, triggered by the Palestinian terrorists' Oct. 7 attack, has already drawn Iran-backed militants in Syria, Lebanon, Iraq and Yemen.
The Hamas attack on southern Israel resulted in the deaths of 1,197 people, mostly civilians, according to an AFP tally based on Israeli official figures.
Militants also seized 251 hostages, 111 of whom are still in Gaza. Thirty-nine of them are believed to be dead.
Israel's retaliatory campaign has killed at least 39,623 people in Gaza, according to the Hamas-run territory's health ministry, which does not give details of civilian and militant deaths.
Even as the region braced for further escalation, Hezbollah and Israel continued their near-daily exchanges of fire.
The Lebanese Health Ministry said four people were killed in two strikes on the border towns of Mais al-Jabal and Hula, while Hezbollah said it targeted military sites in northern Israel with "explosive-laden drones."
Tehran has said it expects Hezbollah to hit deeper inside Israel and no longer be confined to military targets.
The U.S. said it was moving additional warships and fighter jets to the region.
President Joe Biden was scheduled to meet with his national security team Monday "to discuss developments in the Middle East," the White House said.
The cross-border violence since October has killed at least 549 people in Lebanon, mostly fighters but also including at least 116 civilians, according to an AFP tally.
On the Israeli side, including the annexed Golan Heights, 22 soldiers and 25 civilians have been killed, according to army figures.
Far from the Lebanese border, the Israeli military said around 15 rockets crossed from the southern Gaza Strip into Israel on Monday, with medics saying they were treating an injured man.
Months of talks, mediated by Qatar, Egypt and the U.S., aimed at a Gaza cease-fire and a hostage-release deal have repeatedly stalled.