By Maya Gebeily, Timour Azhari and Phil Stewart
WASHINGTON/BEIRUT/JERUSALEM (Reuters) -Lebanese troops pulled back from the border with Israel late on Monday as a ground invasion by Israel looked imminent, just days after Israel killed the head of Lebanese armed group Hezbollah in an escalation of regional tensions.
Israeli strikes hit Beirut's southern suburbs, a security source said, with a Reuters reporter witnessing a flash of light and a series of loud blasts about an hour after the Israeli military warned residents to evacuate areas near buildings it said contained Hezbollah infrastructure south of the Lebanese capital.
A U.S. official speaking on condition of anonymity told Reuters the positioning of Israeli troops suggested a ground incursion of Lebanon could be imminent.
Israeli Defence Minister Yoav Gallant told local council heads in northern Israel that the next phase of the war along Lebanon's southern border would begin soon, and would support the aim of bringing home Israelis who have fled Hezbollah rockets during nearly a year of border warfare.
He also told troops: "We will use all the means that may be required – your forces, other forces, from the air, from the sea, and on land. Good luck."
Lebanese troops pulled back about five kilometres (3 miles) from positions along Lebanon's southern border with Israel, a Lebanese security source told Reuters. A Lebanese army spokesperson did not confirm or deny the movement.
Lebanon's army has historically stayed on the sidelines of major conflicts with Israel, and in the last year of hostilities has not fired on the Israeli military.
Israel declared the areas around the communities of Metula, Misgav Am, and Kfar Giladi in its north near the Lebanon border as a closed military zone.
U.S. State Department spokesperson Matthew Miller said Israel had told the U.S. it is conducting limited ground operations focused on Hezbollah infrastructure in Lebanon near the border.
Washington so far has had little success urging Israel to rein in its assaults on Hezbollah or on the Hamas militia in Gaza.
Israel last week rejected a proposal by the U.S. and France calling for a 21-day ceasefire on the Lebanon border to give time for a diplomatic settlement that would allow displaced civilians on both sides to return home.
U.S. President Joe Biden again called for a ceasefire on Monday.
"I'm more worried than you might know and I'm comfortable with them stopping," Biden told reporters when asked if he was comfortable with Israeli plans for a cross-border incursion. "We should have a ceasefire now."
HEZBOLLAH SAYS IT IS READY TO FACE LAND INCURSION
Friday's assassination of Hassan Nasrallah - the most powerful leader in Tehran's "Axis of Resistance" against Israeli and U.S. interests in the Middle East - was one of the heaviest blows in decades to both Hezbollah and Iran, and followed two weeks of intensive airstrikes.
Hezbollah's deputy leader Naim Qassem, in a first public speech since Nasrallah's death, said that "the resistance forces are ready for a ground engagement."
Nasrallah built Hezbollah - created by Iran in 1982 to fight Israel - into Lebanon's most powerful military and political force, with a wide reach across the Middle East.
Now it must replace a leader who the West branded a terrorist mastermind but who to millions of supporters was a hero who stood up to Israel.
Qassem said it would "choose a secretary-general for the party at the earliest opportunity".
He said Hezbollah had continued to fire rockets as deep as 150 km (93 miles) into Israeli territory.
"We know that the battle may be long," he said. "We will win as we won in the liberation of 2006," he added, referring to the last big conflict between the two foes.
But Israeli Prime Minister Benjamin Netanyahu warned Hezbollah's main backer, Iran, that "there is nowhere we will not go to protect our people and protect our country".
In a three-minute video clip in English that he addressed to the Iranian people, he accused their government of plunging the Middle East "deeper into war" at the expense of its own people, whom it was bringing "closer to the abyss".
Israeli airstrikes have eliminated several Hezbollah commanders but also killed about 1,000 civilians and forced one million to flee their homes, according to the Lebanese government.
At least 95 people were killed and 172 wounded in Israeli strikes on Lebanon's southern regions, the eastern Bekaa Valley, and Beirut in the past 24 hours, Lebanon's health ministry said early on Tuesday.
Rescuers stood on a flattened building. "We are rescuing these people, pulling out the living, the torn apart, and the martyrs," said one, Mazin al-Khatib.
ASSASSINATIONS OF PALESTINIAN MILITANT LEADERS
Israel has also assassinated leaders of the Iranian-backed Palestinian militant group Hamas in the Gaza war, one of them - its political leader Ismail Haniyeh - as he was visiting the Iranian capital in July.
Hours before Qassem spoke, Hamas said an Israeli airstrike had killed its leader in Lebanon, Fateh Sherif Abu el-Amin, along with his wife, son and daughter in the city of Tyre.
Abu el-Amin had worked for the U.N. Palestinian refugee agency UNRWA before being suspended in March. UNRWA chief Philippe Lazzarini told reporters it had not known of his purported Hamas role.
Another faction, the Popular Front for the Liberation of Palestine, said three of its leaders had died in a strike in Beirut's Kola district, the first Israeli attack so close to the city centre.
The Israeli attacks on militant targets in Lebanon are part of a conflict stretching from the Palestinian territories of Gaza and the occupied West Bank to Iranian-backed groups in Yemen and Iraq. The escalation has raised fears that the United States and Iran will be sucked in.
Iranian Foreign Ministry spokesperson Nasser Kanaani said Tehran would not let any of Israel's "criminal acts" go unanswered, referring to the killings of Nasrallah and an Iranian Revolutionary Guard Corps deputy commander who died in the same strikes.