Here is a rundown of what is known about Israel's ground operations so far.

- When did the raids begin?

Late Monday, Israel's military began what it called "limited, localised and targeted raids" against Hezbollah in south Lebanon's border areas.

Its ground forces are backed by fighter jets and artillery fire.

But the scope of Israel's action has not been clear, with United Nations peacekeepers in Lebanon saying it did not amount to a "ground incursion" and Hezbollah denying Israeli troops had crossed the border.

An army statement early Tuesday confirmed troops had started "targeted ground raids" across Israel's northern border, but few details have been provided of the extent of the operation or its timeframe.

An Israeli security official said localised raids had taken place and that they were limited in scope.

The military did not reveal how many soldiers were involved, but said its 98th division -- including paratroopers and commando units -- was taking part.

The division had been previously deployed in the Gaza Strip, where Israeli forces continue to battle Palestinian militants led by Hamas.

Israel's military later announced it was calling up four additional brigades to the border.

On Monday evening, the military declared three areas along the northern border with Lebanon a "closed military zone", providing the first indication of a possible ground offensive.

- What are Israel's targets? -

The military said it was acting on "precise intelligence" targeting Hezbollah positions and infrastructure in southern Lebanon.

"These targets are located in villages close to the border and pose an immediate threat to Israeli communities in northern Israel," it said.

Tuesday's operations come after Israeli air strikes killed several top Hezbollah commanders in recent weeks, including Nasrallah on Friday.

"The elimination of Nasrallah is an important step, but it is not the final one," Defence Minister Yoav Gallant warned on Monday.

"We will use all the means that may be required -- your forces, other forces, from the air, from the sea, and on land," Gallant told soldiers in the north.

- What are Israel's goals? -

Since October 8, Hezbollah has been firing rockets across the border, displacing more than 60,000 residents in northern Israel.

Hezbollah has said it is acting in solidarity with its Islamist ally Hamas in Gaza, following the unprecedented attack on Israel on October 7 that resulted in the deaths of 1,205 people on the Israeli side, according to an AFP tally based on Israeli figures.

The ensuing cross-border clashes have intensified in recent weeks.

While Israel engaged in fierce fighting with Hamas in Gaza, Gallant announced on September 18 that the "centre of gravity" of the war was now pivoting to the north.

"It was now time to ensure that those displaced from the north would be able to return to their homes," he said.

Other officials including Prime Minister Benjamin Netanyahu have repeatedly vowed to return those displaced back to their homes.

"We will continue to hit Hezbollah... the one who has a missile in his living room and a rocket in his home will not have a home," Netanyahu said in a statement last month.

- How has Hezbollah responded? -

Hezbollah on Tuesday said it targeted a disused air base in Tel Aviv in retaliation for attacks on civilians in Lebanon, in an operation it dedicated to Nasrallah.

It said its fighters launched "a salvo of Fadi-4 rockets at the Sde Dov air base in Tel Aviv" after earlier saying it fired Fadi-1s at an intelligence base and Mossad headquarters in Israel's commercial hub.

Hezbollah said it also attacked Israeli troop movements in Metula in northern Israel using artillery and later fired rockets at a "gathering of enemy soldiers" in the same area.

Israeli troops in northern Israel's Avivim were also targeted, Hezbollah added.

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