The death of Bahaa Abu el-Atta and his wife as they slept in their home in eastern Gaza set off the heaviest fighting in months between Israel and Islamic Jihad, an Iranian-backed militant group that is even more hard-line than Gaza's Hamas rulers. Gaza militants fired scores of rockets into Israel throughout the day, some reaching as far as Tel Aviv, while Israeli warplanes responded with a series of airstrikes on Islamic Jihad targets. Eight others were killed, including at least seven militants.
"Whoever thinks that it is possible to hurt our citizens and evade our long arm is mistaken," Prime Minister Benjamin Netanyahu said at a meeting of top security officials at Israeli military headquarters in Tel Aviv.
He described Abu el-Atta as a "ticking time bomb" and "the main instigator of terrorism" from Gaza, responsible for many rocket attacks on Israel and planning more.
He said the killing had been approved 10 days earlier, and that Israel had waited for the "optimal conditions" to hit him while minimizing civilian casualties. He said Israel was not interested in escalation but warned: "This could take time."
Egypt, which frequently mediates between Israel and Gaza militants, was working to de-escalate tensions, according to officials in Cairo. The officials spoke on condition of anonymity because they were not authorized to talk to the media.
In a possible sign the fighting could be brief, Gaza's ruling Hamas militant group did not take part in Tuesday's rocket fire. Although larger and more powerful than Islamic Jihad, Hamas is also more pragmatic. With Gaza's economy in tatters, it appears to have little desire for another round of fighting with Israel.
Netanyahu has repeatedly said in speeches in recent weeks that Iran, Israel's archenemy, is becoming increasingly aggressive across the region and vowed to strike back.
Israel frequently strikes Iranian interests in Syria. But Tuesday's airstrike in Damascus appeared to be a rare assassination attempt of a Palestinian militant in the Syrian capital.
Syria's state-run news agency said Israeli warplanes fired three missiles at the home of Akram al-Ajouri, a member of Islamic Jihad's leadership living in exile. Ajouri was not harmed, but his son and granddaughter were killed, the report said. The Israeli military had no comment.
Despite their bitter rivalry, the two projected a message of unity on Tuesday. Gantz, a former military chief who led a 2014 war against Gaza militants, said he had been consulted by Netanyahu ahead of the overnight airstrike and called it the "right decision."
Both men have expressed support for a unity government between their parties in order to avoid yet another election. But both have demanded that they lead the government.
A successful military operation could bolster Netanyahu as he seeks to stay in power — especially if he is indicted on corruption charges, as expected, in the coming weeks.
Netanyahu has sought to portray himself as the only leader capable of steering Israel through its many security challenges. Remaining prime minister would leave him in the best position to fight any charges, since all other Cabinet ministers must automatically resign if indicted.
Efraim Inbar, president of the Jerusalem Institute for Strategy and Security, said protracted fighting could push the two men toward compromise. "It could be used as a moment for a national unity government," he said.
But Stav Shaffir, a lawmaker with the dovish Democratic Union, questioned the timing and motives of the killing. "It's hard not to ask questions about timing," she tweeted. "Above every decision hovers a cloud of suspicions."
The Gaza airstrike killed Abu el-Atta as he slept at home, destroying the top floor of his apartment building. Abu el-Atta's relatives and the Islamic Jihad said Abu el-Atta's wife was killed and the two wounded were their children.
Islamic Jihad is much smaller than Hamas. But with the strong support of Iran, it has become much more aggressive in its confrontations with Israel. It often acts without Hamas' support.
In recent weeks, Israeli media had identified Abu el-Atta as a senior militant responsible for repeated rocket attacks, including a late-night barrage over the Jewish sabbath two weeks ago. His father said the Islamic Jihad commander had been in hiding in recent weeks, fearing he would be targeted.
Minutes after the group confirmed the death, rockets were fired toward Israel. Air raid sirens continued to go off throughout the day as far away as Tel Aviv.
By nightfall, the army said nearly 200 rockets had been fired, with about half landing in open spaces and dozens more intercepted by Israel's Iron Dome defense system. But in one instance, a rocket landed on a highway, just meters (yards) from a passing vehicle. In another, a rocket pierced the roof of a residential home.
The Mada rescue service said two people were treated for shrapnel wounds.
In response, Israel shut down crossing points into Gaza and reduced the permissible fishing area off the territory's coast to 6 nautical miles. Schools were closed, and people were told to stay home in communities stretching from the Gaza border all the way to Tel Aviv, about 90 kilometers (55 miles) away. Public shelters were opened and restrictions were placed on large gatherings.
As the rocket fire persisted, Israel struck a series of Islamic Jihad targets throughout Gaza, killing at least three militants.
The attacks also came at a difficult time for Islamic Jihad's Iranian patrons, who are struggling under crippling U.S. sanctions.
Iran's regional influence is also being challenged by unprecedented, economically driven mass protests in Iraq and Lebanon — two countries where Tehran wields major influence. Tehran fears the unrest could spark a backlash against its proxies in those countries, and Supreme Leader Ayatollah Ali Khamenei has accused the U.S. and its regional allies of fomenting it.
Akram reported from Gaza City, Gaza Strip. Associated Press writers Patty Nieberg in Jerusalem, Zeina Karam in Beirut and Albert Aji in Damascus contributed.