The U.S. Embassy in Lebanon renewed its call for citizens to leave Lebanon immediately as the Middle East war expanded to Lebanon.

Several strikes hit Beirut's southern suburbs on Monday after Israeli evacuation warnings, as Israel attacked the country following Hezbollah's dawn missile launches.

The Israeli military said it killed the head of Hezbollah's intelligence services, Hussein Moukalled, in a strike in Dahieh overnight.

"The IDF now confirms that in a precise strike in Beirut last night (Sunday), the terrorist Hussein Moukalled, who served as the head of Hezbollah's intelligence headquarters, has been eliminated," the army said in a statement on Monday.

Israeli Defense Minister Israel Katz warned Monday that Israel would send Hezbollah chief Naim Qassem to "the bottom of hell" like Iran's supreme leader Ayatollah Ali Khamenei, after an attack by the Lebanese armed group.

"We will strike Hezbollah hard, and Naim Qassem, chairman of the Hezbollah terrorist organization, will discover that whoever follows Khamenei's path ends up like Khamenei -- at the bottom of hell," Katz said during a visit to the Israeli air force operations center.

Lebanon's government has decided on an "immediate ban" of Iran-backed Hezbollah's military and security activity, Prime Minister Nawaf Salam said Monday, in an unprecedented move as Israel retaliated to rocket fire.

Israel's military said Monday there was no reason to launch a ground invasion of Lebanon "imminently" after an overnight attack from Hezbollah prompted Israel to retaliate with air strikes.

"There is nothing on the ground that constitutes going into ground invasion.. imminently," military spokesman Lieutenant Colonel Nadav Shoshani told journalists on whether Israel would send troops in Lebanon.

Israel's military said Monday it struck a senior Hezbollah operative in Beirut, with the defense minister saying the Lebanese group's chief Naim Qassem is "a marked target".

"A short while ago, the (Israeli military) precisely struck a senior Hezbollah terrorist in Beirut," the military said. AFPTV showed smoke rising from the southern Beirut district of Dahieh, a stronghold of Hezbollah.

Iran’s army said Monday it targeted US Ali Al Salem air base in Kuwait as well as vessels in the Indian ocean after the killing of the Islamic republic’s supreme leader in U.S. and Israeli strikes.

"Missile units of the army’s ground and naval forces operating from various locations targeted the U.S. Ali Al Salem air base in Kuwait as well as enemy vessels in the northern Indian Ocean over the past hours," the army said in a statement.

Israel’s military chief Eyal Zamir said fighting against Lebanese militant group Hezbollah, which began early Monday, could take "many" more days.

"We have launched an offensive campaign against Hezbollah," Zamir said in a video shared by the military on Monday, hours after rocket fire claimed by Hezbollah prompted a wave of Israeli strikes on Lebanon. "We must be prepared for several days of fighting, many."

Israel and Hezbollah traded fire on Monday, while President Donald Trump vowed to avenge the deaths of U.S. service members and said the war with Iran could last for weeks.

The European Union has warned of the cost to the Middle East of a long war, and said it was reinforcing its naval mission in the Red Sea.