JERUSALEM // Hamas’s military chief was killed yesterday in Israel’s most violent attack on Gaza since its invasion four years ago. Ahmed Al Jabari, 52, commander of the Izz Al Din Al Qassam Brigades, was one of nine people, two of them children, who died in the first of more than 20 Israeli air strikes. Thirty people were injured. The air strikes mark the resumption of Israel's policy of targeted assassinations, after Gaza militants ended an uneasy truce last Saturday and fired more than 100 rockets into <a href="gopher://topicL3RoZW5hdGlvbmFsL0xvY2F0aW9uL01pZGRsZSBFYXN0L0lzcmFlbA==" inlink="topic::L3RoZW5hdGlvbmFsL0xvY2F0aW9uL01pZGRsZSBFYXN0L0lzcmFlbA==">Israel</a> in four days. Militants in Gaza vowed revenge yesterday. Al Qassam Brigades said: “The occupation has opened the gates of hell on itself”, and its militants would “continue the path of resistance”. Hamas said: “The Palestinian government mourns the loss of the senior Palestinian leader Ahmed Al Jabari, one of the symbols of the resistance, and holds the occupation responsible for the consequences of this crime.” The Palestinian president <a href="gopher://topicL3RoZW5hdGlvbmFsL1Blb3BsZS9MZWFkZXJzIGFuZCBwb2xpdGljaWFucy9NYWhtb3VkIEFiYmFz" inlink="topic::L3RoZW5hdGlvbmFsL1Blb3BsZS9MZWFkZXJzIGFuZCBwb2xpdGljaWFucy9NYWhtb3VkIEFiYmFz">Mahmoud Abbas</a> condemned the attacks, demanded an immediate end to the bloodshed and called for an emergency meeting of the Arab League "to discuss the dangerous Israeli escalation and brutal aggression on our people in the Gaza Strip". But Israel warned that the air strikes were only the beginning of a sustained campaign that may include another invasion. The aim was “the targeting of terrorist organisations in the Gaza Strip – Hamas, Islamic Jihad and others”, the military said. “All options are on the table. If necessary, the IDF is ready to initiate a ground operation in Gaza.” Yesterday's attacks began with an air strike on Al Jabari's saloon car near the busy Omar Mukhtar Street in Gaza City. Crowds of people and security personnel rushed to the scene of the strike, trying to put out the fire that had engulfed the car and left it a charred shell. The <a href="gopher://topicL3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvSGFtYXM=" inlink="topic::L3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvSGFtYXM=">Hamas</a> commander's body and that of a bodyguard were pulled from the burnt-out wreckage. Al Jabari was one of the most influential Hamas leaders in Gaza, had long been at the top of Israel’s most-wanted list and survived four previous attempts to kill him. He was blamed for a string of attacks, including the 2006 capture of Gilad Shalit, the Israeli soldier released last year in a prisoner swap for 1,027 Palestinians. He personally escorted Shalit to the Egyptian border on the day of his release. Al Jabari was originally a member of <a href="gopher://topicL3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvRmF0YWg=" inlink="topic::L3RoZW5hdGlvbmFsL09yZ2FuaXNhdGlvbnMvRmF0YWg=">Fatah,</a> Hamas's rivals, but joined the Islamist group while serving 13 years in prison and became operational head of the Brigades in 2002. He played a leading role in Hamas's takeover of the Gaza Strip in June 2007. Although technically second-in-command, he controlled the group’s military activities, said Walid Al Mudallal, a political-science professor at the Islamic University of Gaza. “This is a significant leader in Hamas and I think it will respond massively to his assassination,” Mr Mudallal said. “I’m not sure if we’re talking about full-blown war, but definitely an escalated cycle of violence will be the result of this.” Critics say Israel’s assassination policy invites retaliation by militants and encourages them to try to assassinate Israeli leaders. Advocates counter that they are an effective deterrent without the complications of a ground operation, which results in chiefly civilian and Israeli troop casualties. Proponents argue they also prevent future attacks by removing their masterminds. The Israeli vice prime minister Moshe Yaalon, the army chief of staff at the time targeted killings surged, is convinced the practice worked. “Clearly over these past 13 years there has been an ongoing war, but there have also been extended periods of calm,” Mr Yaalon said on Monday. "When I was chief of staff, the targeted killings against Hamas led to extended periods of quiet."<br/><br/>hnaylor@thenational.ae * With additional reporting the by Associated Press and Agence France-Presse Follow <strong>The National </strong> on & Hugh Naylor on