Hezbollah fired overnight anti-aircraft missiles on Israeli warplanes in south Lebanon, forcing them to retreat beyond the border.

The group had launched rockets at northern Israel Thursday "in response" to a deadly Israeli strike in south Lebanon -- the group's first attack after Israel killed a top commander earlier this week.

A Syrian family of four were killed Thursday in an Israeli strike on their house in the southern village of Shamaa in the Tyre district.

A mother and her three children were killed as Israeli warplanes targeted their house, local media reports said. Several others were injured in the strike.

Prime Minister Benjamin Netanyahu said on Thursday that Israel was prepared for any "aggression" against it following threats of retaliation for the killings of top Hamas and Hezbollah figures.

"Israel is at a very high level of preparation for any scenario, both defensive and offensive. We will make any act of aggression against us pay a very high price... Those who attack us, we will attack in return," Netanyahu said in a statement.

Iran and armed groups backed by it are preparing coordinated action meant to deter Israel but avert all-out war, sources and analysts said, after the killings of top Hamas and Hezbollah figures.

On Wednesday, Iranian officials met in Tehran with representatives of the so-called "axis of resistance" -- a loose alliance of Tehran-backed groups hostile to Israel -- to discuss retaliation for the deaths of Hamas's leader and Hezbollah's top military commander, said a source close to Lebanese group.

The Iran-aligned "axis of resistance" against Israel and its allies have lost two major figures in less than 24 hours in attacks either blamed on or claimed by Israel.

Hamas political chief Ismail Haniyeh was killed on Wednesday in Tehran in a strike the group blamed on Israel, hours after top Hezbollah commander Fouad Shukur perished in an Israeli strike on southern Beirut.

Hezbollah chief Sayyed Hassan Nasrallah warned Thursday that the group was bound to respond to Israel's killing of its top military commander Fouad Shukur, saying his death and that of Hamas leader Ismail Haniyeh "crossed" red lines.

"You do not know what red lines you crossed," he said, addressing Israel during a speech broadcast at Shukur's funeral.

The U.S. has deployed at least 12 warships to the Middle East, including the aircraft carrier USS Theodore Roosevelt, amphibious assault teams and over 4,000 Marines and sailors, in response to escalating tensions in the region following the assassinations of Hamas leader Ismail Haniyeh in Tehran and Hezbollah military chief Fouad Shukur, the Washington Post reported on Thursday, citing a Pentagon official.

Israel has communicated a “stern warning” to Hezbollah through Western and regional intermediaries following the recent assassination of top commander Fouad Shukur that any massive attack on Israeli civilians will lead to war, Israeli sources told the Yedioth Ahronoth newspaper.

“Israel intends to target fighters rather than combat-supporting infrastructure and urges Hezbollah to adopt a similar focus,” the sources added.

Britain’s Foreign Secretary David Lammy and Defense Secretary John Healey arrived Thursday in Beirut following a trip to Qatar.

They met with Speaker Nabih Berri and caretaker Foreign Minister Abdallah Bou Habib following their arrival before heading to the Grand Serail for talks with caretaker Prime Minister Najib Mikati.

By Asher Kaufman, University of Notre Dame

Israel's apparent assassinations of Fouad Shukur, Hezbollah's top military leader, in Beirut, and Hamas political leader Ismail Haniyeh, in Tehran, have raised again the specter of a regional war involving regional adversaries – one that could potentially drag the United States into the fray.