The Israeli military carried out airstrikes in Gaza on Friday in what it described as "operation breaking dawn," killing a commander of the Palestinian Islamic Jihad (PIJ) militant group, Tayseer Jabari.
Shortly after the airstrike, Ziyad al-Nakhalah, the leader of PIJ, announced that there would be "no red lines" and that the militant group would target Tel Aviv with "resistance fire."
Formed in 1981, PIJ is a smaller and more hardline Palestinian militant group than Hamas, which controls the Gaza Strip.
In November 2019, the Israeli military killed Jabari's predecessor, Baha Abu al-Ata, in a targeted strike. In retaliation, PIJ launched rockets at Tel Aviv, injuring several civilians, which prompted further strikes from Israel into Gaza.
Video footage showed smoke billowing from an apartment in Gaza city that was hit on Friday afternoon.
The death toll was not immediately clear. The Hamas-run ministry of health said that four Palestinians were killed in the Israeli airstrike and 30 people were injured. Israeli media reports quoted Israeli military officials as saying that 15-20 PIJ militants had been killed.
The health ministry in Gaza said that a five-year-old girl was among the dead.
Israel's interior minister, Ayelet Shaked, has warned that the country could be facing a "lengthy" round of fighting with Gaza. "We don’t know how this will play out but this could take time. This could be a lengthy round [of violence] and a hard one," she told Israeli broadcaster Channel 12.
Speaking on the Gaza operation, Israeli army spokesman Richard Hecht described the operation as a "pre-emptive attack" and said: "We haven't finished yet."
Yair Lapid, the Israeli prime minister, said that the airstrikes were intended to avert a "concrete threat" of Palestinian cross-border attacks following a series of threats from militants in Gaza over the detainment of a senior PIJ leader.
The attack comes after several days of high tension between Israel and Gaza over the arrest of PIJ's leader in the West Bank earlier this week.
There were unconfirmed reports on Friday of casualties after the airstrike which is said to have targeted a senior PIJ figure.
Israel had closed roads around Gaza earlier this week and sent reinforcements to the border as it braced for a revenge attack after the arrest of a senior member of the Islamic Jihad militant group in the occupied West Bank on Monday.
Israel and the Hamas militant group have fought four wars and several smaller skirmishes in the 15 years since it seized power from rival Palestinian forces.
'We will not hesitate to defend our citizens'
Israeli Defense Minister Benny Gantz visited communities near Gaza on Friday, saying authorities were preparing "actions that will remove the threat from this region," without elaborating.
"We will operate with internal resilience and external strength in order to restore routine life in Israel's south," he said, "We do not seek conflict, yet we will not hesitate to defend our citizens, if required."
The latest escalation began when Israeli forces arrested a senior member of the Islamic Jihad militant group in the West Bank town of Jenin late Monday. A teenage member of the group was killed in a gun battle between the Israeli troops and Palestinian militants.
Ahmed Mudalal, an Islamic Jihad official in Gaza, said the group had made demands of Israel through Egyptian mediators, including the release of the detained militant and another prisoner, a halt to West Bank raids and the lifting of the Gaza blockade. He said they have not yet received a response.
Earlier on Friday, a couple of hundred Israelis protested near the Gaza Strip on Friday to demand the return of a captive and the remains of two Israeli soldiers held by Hamas.
The protesters were led by the family of Hadar Goldin, who along with Oron Shaul was killed in the 2014 Gaza war. Hamas is still holding their remains, as well as two Israeli civilians who strayed into Gaza and are believed to be mentally ill, hoping to exchange them for some of the thousands of Palestinian prisoners held by Israel.
The protesters pushed through two police checkpoints on a road near the heavily-guarded Gaza frontier before stopping at a third.