An Israeli airstrike targeted the suburbs of Beirut on Tuesday, killing a senior commander of Iran-backed Hezbollah, the Israeli military said, raising fears of the Israel-Hezbollah conflict escalating into a broader regional war.

The Israeli military carried out the airstrike in retaliation for a Saturday rocket attack on a soccer pitch in Golan Heights, which killed 12 minors. Israel and the US blamed Hezbollah for the attack, though the Shiite group denied responsibility.

The Tuesday airstrike killed Fuad Shukr, the "right-hand man" of Hezbollah Secretary-General Hassan Nasrallah who served as his adviser for planning and directing wartime operations, the Israel Defense Forces (IDF) said.

Three people have been killed and 74 others injured in the Israeli airstrike, Lebanon's Health Ministry announced. However, it did not identify the victims.

Al-Arabiya and Al-Hadath earlier confirmed that Fuad Shukr had been killed in the airstrike, and his body transferred to Beirut's Great Prophet Hospital.

"Fuad Shukr has directed Hezbollah's attacks on the State of Israel since October 8th, and he was the commander responsible for the murder of the 12 children in Majdal Shams in northern Israel on Saturday evening, as well as the killing of numerous Israelis and foreign nationals over the years," the IDF said in a statement.

"As the Head of Hezbollah's Strategic Unit, Fuad was responsible for the majority of Hezbollah's most advanced weaponry, including precise-guided missiles, cruise missiles, anti-ship missiles, long-range rockets, and UAVs. He was responsible for force build-up, planning, and execution of terror attacks against the State of Israel," the statement added.

The White House doubled down on its support for Israel in reaction to the strike that killed Shukr. “Our commitment to Israel’s security is ironclad and unwavering against all Iran-backed threats, including Lebanese Hezbollah,” National Security Council spokesperson Adrienne Watson said in a statement.

Vice-President Kamala Harris also said she “unequivocally” supports Israel’s right to defend itself "against the terrorist organization, which is exactly what Hezbollah is."

Iran's Foreign Ministry spokesman strongly condemned the Israeli airstrike, calling it a "clear violation of Lebanon's sovereignty and territorial integrity and a blatant violation of international rules and the UN Charter."

Iran's UN envoy in a letter to the Security Council said Israel's "cowardly" attack must be "unequivocally and immediately condemned by the Security Council."

"The Security Council must also take immediate action in response to this criminal act to ensure that such aggression, which threatens regional peace and security, is not repeated. Israel must be held accountable for these atrocities and cannot go unpunished," the letter said.

Iran’s newly elected president had earlier warned Israel of serious repercussions if it attacks Lebanon.

The hostilities between Israel and Hezbollah, largely triggered by the war in Gaza, are their worst since the 2006 conflict.

The clashes have largely been confined to the border area, with both sides previously expressing that they do not desire a broader conflict. However, the situation has raised concerns about the potential escalation towards war.

US attack on Iran-backed militants in Iraq

Shortly after the Israeli attack in Lebanon, the US military also carried out an airstrike targeting Tehran-backed combatants in Iraq who were allegedly attempting to launch one-way attack uncrewed aerial systems, Al-Arabiya reported, citing a US official.

“Based on recent attacks it was assessed that the UAS posed a threat to US and Coalition Forces,” the report said.

The US official did not provide further details, but Reuters cited Iraqi police and medical sources as saying that blasts inside a base used by Iran-backed Popular Mobilization Forces (PMF) militants south of Baghdad on Tuesday killed one member and wounded seven others.

The attack came a few days after a US military base in Syria's Conoco gas field was attacked for the second time in 24 hours with more than ten rockets fired from areas controlled by Iran-backed militants.

Over the past ten months, American bases in Iraq and Syria have been frequently attacked by Iran-backed militants, particularly the Islamic Resistance in Iraq, a coalition of Tehran's proxies which includes groups like Kataib Hezbollah, also a member of the Popular Mobilization Forces (PMF).