Israeli forces have captured a strategic mountain and the Crusader-era Beaufort Castle in southern Lebanon, marking their deepest military incursion into the country in more than 25 years, the Israeli military said on Sunday.

The takeover of the fortress, located near the city of Nabatiyeh, followed days of heavy fighting and air strikes in surrounding villages, where Israeli troops engaged Hezbollah fighters in the rugged terrain, according to military statements.

Israel said the operation was launched several days ago in the Beaufort Ridge area and the adjacent Suluki Valley to dismantle Hezbollah infrastructure and remove what it described as “direct threats to Israeli civilians.”

The army added that it was prepared to expand the operation if necessary.

Israeli military spokesperson Avichay Adraee posted images on social media showing troops at the site, while Defence Minister Israel Katz said Israeli forces had raised the national flag over the castle.

The site was previously held by Israel between 1982 and its withdrawal from Lebanon in 2000.

The advance comes despite a nominal ceasefire in place since April 17 and ahead of scheduled indirect talks in Washington on June 2 and 3.

Israeli troops have reportedly crossed the Litani River, a former de facto boundary, and are operating in villages closer to Nabatiyeh, roughly 5 kilometres away, with evacuation warnings issued for nearby towns including Tyre.

Israel has declared a broad area between the Litani and Zahrani rivers a combat zone, as its forces continue operations in southern Lebanon.

Some residents have fled amid intense strikes, though many remain in affected areas.

There was no immediate response from Hezbollah or the Lebanese government to the latest advance.

However, Hezbollah said it carried out attacks overnight targeting Israeli troops and a Merkava tank near the border town of Bayada, and claimed ongoing clashes in multiple areas north of the Litani.

According to Lebanese authorities, the fighting has killed more than 3,300 people and displaced over one million.