What does this attack mean for people in the region – and does it signal a major escalation in the border war that Israel and Hezbollah have been fighting over the Lebanese frontier?
Israel was adamant that Iran-backed Hezbollah was responsible for the assault on a football pitch in the community of Majdal Shams.
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In scenes described as gruesome by first responders, paramedics tried to save the lives of a group of young people who were caught in the blast. Officials say 12 died with another 20 suffering injuries. The casualties ranged in age between 10 and 20.
Israel’s chief military spokesman Daniel Hagari said the rocket was launched from an area near a village called Chebaa in southern Lebanon.
Forensic analysis indicates that that rocket was an Iranian-made Falaq-1 rocket, fitted with a 50kg (110lb) warhead.
Earlier on Saturday, Hezbollah announced on social media that it had fired a Falaq-1 at an “Israeli military headquarters” as part of its rocket launches throughout the day.
These barrages followed an Israel Defence Forces (IDF) airstrike that killed four people in southern Lebanon. Israel said it had struck at a Hezbollah military cell.
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In a televised statement, Mr Hagari said there has been no change in Israel’s Home Front Command’s operating instructions.
This suggests that the IDF is not expecting an imminent escalation in the conflict on the border.
In what was an unusual move for Hezbollah, a media representative publicly denied responsibility: “The Islamic Resistance has absolutely nothing to do with the incident, and categorically denies all false allegations in this regard.”
Certainly, the deaths of 12 youngsters in a community playground are not something that this powerful political and military organisation wants to be associated with.
Israeli Prime Minister Benjamin Netanyahu shortened his trip to the United States and is expected to convene a meeting of his security cabinet. As expected, he has promised a significant response.
“Hezbollah will pay a heavy price, the kind it has thus not paid,” said Mr Netanyahu in a phone call with the leader of the Druze community in Israel. The majority of those who live in Majdal Shams are Arabic speakers who practice the Druze faith.
But despite the significance and tough words, both Israel and Hezbollah have been trying to avoid all-out war since the fighting began on 8 October – and that reality seems unlikely to change at the moment.