Israel said late Tuesday it had struck sites "throughout Lebanon," targeting what it called Hezbollah rocket launching infrastructure after a series of air raid sirens in northern Israel.

Hezbollah chief Sheikh Naim Qassem said Tuesday that Hezbollah is in a position of "legitimate defense" in the battle against Israel, "defending the land, rejecting surrender, and protecting the nation's existence and independence."

President Joseph Aoun made two phone calls Tuesday to Minister of National Defense Michel Menassa and Army Commander General Rodolphe Haykal, offering his condolences for the death of three soldiers in the South as a result of an Israeli airstrike on the Zibdine-Nabatieh road.

Former Israeli minister Ron Dermer has confirmed for the first time that he has returned to work for Prime Minister Benjamin Netanyahu and that he has been appointed to lead negotiations with the Lebanese government.

Threats from Israeli officials to unleash Gaza-level destruction on Lebanon are "wholly unacceptable", the U.N. said Tuesday, and warned that "deliberately attacking civilians or civilian objects amounts to a war crime".

Israel has stepped up strikes and deployed ground troops to its northern neighbor since March 2, when Lebanon was dragged into the Middle East war after Tehran ally Hezbollah attacked Israel with rockets in retaliation for the killing of Iranian supreme leader Ali Khamenei.

Youssef Assaf was in a Lebanese Red Cross ambulance when it was targeted by an Israeli strike near Tyre, in southern Lebanon. The 35-year-old paramedic died of his wounds two days later.

"I was called around 10:30 pm and told that he was wounded and in the hospital," his wife, Jeanne d'Arc Boutros, told AFP from northern Lebanon, where she had fled to a relative's home.

Lebanon transferred more than 130 Syrian detainees to their home country on Tuesday, a Lebanese judicial official told AFP, as part of an agreement the two sides signed in February.

Overcrowded Lebanese prisons host more than 2,200 Syrians held on various charges.

With airstrikes rocking Beirut and Israeli troops trying to advance against Hezbollah, Lebanon's government has broken a taboo by proposing the first direct talks with Israel in decades. But Lebanese officials say they want the fighting to end first — and it might be too late for that.

Hezbollah's decision to enter the wider Iran war by firing rockets at Israel has led to the heavy Israeli bombardment of southern Lebanon and Beirut's southern suburbs, killing some 850 Lebanese and driving over a million people from their homes.

Israeli strikes and shelling targeted on Tuesday afternoon several regions in south Lebanon including al-Qsaybeh, Shhour, Jabshit-Harouf, Mayfadoun-Shawkin, Dweir and Deir al-Zahrani, al-Kharayeb, al-Taybeh, Kfartebnit, Arnoun, Aita al-Shaab, and Ramia.

At least nine people were killed in strikes on the south Tuesday, including three Lebanese army soldiers.

U.S. Ambassador to Lebanon Michel Issa, who visited Speaker Nabih Berri on Monday, carried a fundamental question: who in Lebanon actually has the capacity to implement and fulfill commitments as to any possible agreement with Israel to stop the current war, the Nidaa al-Watan newspaper reported.