Israel said intense fighting erupted with Hezbollah in south Lebanon on Tuesday after its paratroops and commandos launched raids there, at the start of a ground incursion and after devastating airstrikes against Hezbollah's leadership.

The Israeli military said the operations in Lebanon began on Monday night and involved the elite 98th division, which was deployed to the northern front two weeks ago from Gaza where they had been fighting against Hamas for months.

It said its air force and artillery supported ground troops engaged in "limited, localised, and targeted ground raids" against Hezbollah in southern Lebanon villages that posed "an immediate threat to Israeli communities in northern Israel".

Two Lebanese seucrity sources told Reuters that Israeli units had crossed into Lebanon overnight for reconnaissance and probing operations. Lebanese troops also pulled back from positions along the border, the source added.

Hezbollah said on Tuesday it had launched rocket and artillery attacks against Israeli troops at positions within Israel, and made no mention of Israeli forces within Lebanon.

The Israeli military issued a warning to citizens not to move in their vehicles from the area north of the Litani river to its south. It has previously said it wants to clear Hezbollah from south of the river.

Israel has dealt heavy blows to Hezbollah, Iran's most powerful Middle East proxy, assassinating its leader Hassan Nasrallah in Beirut last week, eliminating a towering figure who turned the group into Lebanon's top military and political force.

Despite its biggest successes against Hezbollah in decades, Israel has indicated it is primed for a full-fledged invasion of Lebanon with the stated aim of enabling thousands of its citizens who fled Hezbollah rockets to safely return to their communities near the northern border.

Iran's allies -- from Hezbollah to Yemen's Houthis to armed groups in Iraq -- have weighed in with attacks in the region in support of Hamas in the Gaza war, raising fears the conflict will engulf the Middle East and suck in the United States and Tehran.

Yemen's Houthi movement targeted Israeli military posts in Tel Aviv and Eilat with drones on Tuesday, the group's military spokesperson Yahya Saree said in a televised speech.

Lebanese army pulls back

The Lebanese Army said in a statement on Tuesday that its pullback was part of a regular repositioning of some of its monitoring points in southern Lebanon.

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.

Local residents in the Lebanese border town of Aita al-Shaab reported heavy shelling and the sound of helicopters and drones overhead. Flares were repeatedly launched over the Lebanese border town of Rmeish, lighting up the night sky.

An Israeli strike in Lebanon early on Tuesday targeted Mounir Maqdah, commander of the Lebanese branch of the Palestinian Fatah movement's military wing, the Al-Aqsa Martyrs Brigade, according to two Palestinian security officials.

His fate was unknown.

The strike hit a building in the crowded Ain al-Hilweh Palestinian refugee camp near the southern city of Sidon, the sources said. It marked the first strike on Lebanon's largest Palestinian camp since cross-border hostilities between Hezbollah and Israel broke out nearly a year ago.

Israel has not commented on the strike.

In Syria, three civilians were killed and nine others injured in an Israeli airstrike on the capital Damascus, Syrian state media said on Tuesday citing a military source. Israel's military said it does not comment on foreign media reports.

Israel has been carrying out strikes against Iran-linked targets in Syria for years but has ramped up raids since the Palestinian militant group Hamas attacked Israel's southern territory on Oct. 7, 2023.

Hamas killed 1,200 people and took about 250 hostage in its assault on Israel, according to Israeli tallies. Israel in response launched a massive assault on Hamas in Gaza, reducing most of the Palestinian territory to rubble, displacing most of its 2.3 million people and killing more than 41,300 Palestinians, according to the Gaza health ministry.

Strikes on Beirut

Israel's operations in Lebanon follow its deadly detonation of booby-trapped Hezbollah pagers, two weeks of airstrikes, and its killing on Friday of Nasrallah.

The intensive air strikes 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.

Overnight, a series of strikes hit Beirut's southern suburbs after the Israeli military warned residents to evacuate areas near buildings it said contained Hezbollah infrastructure south of the capital.

In the past 24 hours, at least 95 people had been killed and 172 wounded in Israeli strikes on Lebanon's southern regions, the eastern Bekaa Valley, and Beirut, Lebanon's health ministry said early on Tuesday.

The White House and the U.S. State Department did not immediately respond to a request for comment on Israel's ground operations in Lebanon, but on Monday, U.S. President Joe Biden had called for a ceasefire.