In eastern Gaza, the Israeli strike killed Bahaa Abu el-Atta and his wife, setting off a furious barrage of rocket attacks reaching as far as the Tel Aviv heartland as Islamic Jihad vowed further revenge. The Israeli military says Abu el-Atta was the mastermind of recent attacks against it, and responsible for most of the rocket, sniper and drone fire from the region.
Meanwhile, Syrian state media said an Israeli airstrike in the capital, Damascus, targeted another Islamic Jihad commander, Akram al-Ajouri, who was not harmed.
The Israeli military had no comment on the strike in Damascus. Syria's state-run news agency said Israeli warplanes fired three missiles at al-Ajouri's home, killing his son and granddaughter.
The sudden surge in violence looked to awaken Israel's increasingly open conflict with Iran and its proxies in the region. The Israeli government has been criticized by southern border residents for its relative inaction in response to recent militant attacks. The Cabinet was holding an emergency meeting to discuss further action in Tel Aviv.
The airstrikes come at a tenuous time politically for Israel, as Prime Minister Benjamin Netanyahu leads a caretaker government after two inconclusive elections. His chief challenger, former military chief Benny Gantz, is currently trying to build a coalition government of his own.
Lt. Col. Jonathan Conricus, a military spokesman, told reporters that Abu el-Atta was a "ticking time bomb," saying he had been responsible for a number of recent rocket attacks on southern Israel and claimed that he was actively planning new attacks.
"We essentially over the last week have been waiting for the opportune moment to conduct this surgical strike," he said.
Conricus added that the airstrike had been carried out with a warplane that destroyed only the floor of the building where Abu el-Atta was hiding in order to minimize "collateral damage."
The airstrike damaged the half of the second and most of the third floor of a house in the Shejaeya neighborhood, in the eastern part of Gaza City. The house was known to be Abu el-Atta's home. His relatives and the Islamic Jihad said the woman killed in the strike was Abu el-Atta's wife and the two wounded were their children.
The militant group said Abu el-Atta, 42, was undergoing "a heroic act" when he was assassinated. It did not elaborate, but vowed revenge.
Minutes after the Iran-backed group confirmed the death, barrages of rockets could be heard fired toward Israel. Air raid sirens continued to go off throughout the morning, in rapid succession, as far as Tel Aviv.
Israel also shut down crossing points into Gaza and reduced the permissible fishing area off the territory's coast to 6 nautical miles in anticipation of a looming confrontation and schools were canceled in Israeli communities and towns along the Gaza Strip's boundary and all the way to Tel Aviv, about 90 kilometers (56 miles) north of Gaza.
Islamic Jihad often carries out attacks independent of Hamas, the larger militant group that controls Gaza. Conricus described Abu el-Atta as a powerful figure in Gaza who often acts alone without instruction from Tehran or Hamas.
Israel had no further plans to resume its assassinations of militant leaders — a practice that in the past has triggered heavy fighting. "There was no other choice," Conricus said.
In Damascus, a military official said Israeli warplanes fired three missiles toward the Syrian capital, with one being destroyed by Syria's air defenses before reaching its target.
The two others struck the home of al-Ajouri in the Mezzeh neighborhood, the official said. Al-Ajouri's son Muath was killed, along with his granddaughter Batoul. A second man identified as Abdullah Yousef Hassan was killed and nine civilians wounded, the unidentified official said according to Syrian state-media.
An Associated Press reporter at the scene said the attack destroyed the three-story building in Damascus, located on a main highway about 50 meters (yards) across from the Lebanese Embassy. The building was blackened, its windows blown out. Civil defense workers were at the scene, lifting debris and tending to electricity cables. Power had gone off in the neighborhood from the attack.
Just this week Netanyahu appointed hard-line politician Naftali Bennett as Israel's new defense minister. Bennett has long advocated tougher action against Palestinian militants, including a resumption of targeted killings. But he hasn't taken office yet and the military said the operation had been planned long in advance.
Israel routinely says it holds hold Hamas responsible for any fire emanating from the enclave but acknowledges that the vast majority of attacks are carried out by the smaller and more radical Islamic Jihad group.
Since Hamas took over Gaza by force in 2007 from the internationally backed Palestinian Authority, Israel and Gaza militants have fought three wars, with the third in 2014 lasting for 50 days. It was the deadliest and most destructive.
Short-but-frequent spasms of violence have occurred, the latest earlier this month when about 10 projectiles were fired at Israel, which accused Abu el-Atta of being behind them.
Since the 2014 war, Israel has mostly refrained from targeted assassinations of senior Gaza militants, but did so one time in May, Israeli airplanes killed a Hamas commander and financial broker in a car traveling in Gaza City during a three-day exchange of fire.
For Tehran, Tuesday's targeted attacks on leaders of the Iran-backed Islamic Jihad come at a vulnerable moment as Iran struggles 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. The protests are creating unrest that Tehran fears would spark a backlash against Iran-backed proxy militias in those countries and Supreme Leader Ayatollah Ali Khamenei has accused the U.S. and its regional allies of fomenting the Iraq and Lebanon unrest.