Hezbollah Secretary General Hassan Nasrallah said Thursday that Israel had “crossed a red line” in the killing of Hezbollah military chief Fuad Shukr and must expect “rage and revenge on all the fronts supporting Gaza.”

Claiming the fighting had entered “a new phase,” he said Israelis “will weep terribly” in the days ahead.

Nasrallah spoke as Israel braced for Hezbollah’s response as well as for Iranian retaliation in the wake of Hamas political chief Ismail Haniyeh’s death in Tehran early Wednesday. Jerusalem has not taken responsibility for the latter, but has been blamed by Tehran and Hamas.

Shukr’s killing on Tuesday evening was the most serious blow to the Iran-backed terror group in nearly two decades and threatened to push the tit-for-tat exchanges across the Israel-Lebanon border in parallel with the Gaza war into a full-blown regional conflict.

In a televised address at Shukr’s funeral, Nasrallah said Hezbollah was “paying the price for its support for Gaza and the Palestinian people” but said that the group was now beyond the support phase, declaring an “open battle on all fronts.”

Speaking at the same time, Prime Minister Benjamin Netanyahu said Israel was prepared for any “aggression” against it.

“Israel is very prepared for any scenario — both defensively and offensively,” he said. “We will exact a very heavy price for any act of aggression against us from any arena.”

Nasrallah said he had ordered Hezbollah forces in southern Lebanon to curb the fighting on Wednesday and Thursday but that they would resume with higher intensity on Friday, reiterating that the only way to end the war on the Lebanese front was for Israel to stop its “aggression” in Gaza.

Nasrallah repeated Hezbollah’s claim — rejected by Israel and the US — that the terror group was not behind the Saturday rocket attack on the Druze town of Majdal Shams in the Golan Heights in which 12 children were killed.

He claimed Hezbollah would have admitted if it had made a mistake and killed civilians, and suggested it could have been an Israeli interceptor that hit Majdal Shams. Weapons experts have said all evidence points to a rocket from Lebanon hitting the soccer field and killing the children.

The Hezbollah leader argued Shukr’s assassination was not actually a response to the Majdal Shams incident but rather an act of war.

Nasrallah said unnamed countries had asked his group to retaliate in an “acceptable” way — or not at all. But he said it would be “impossible” for the group not to respond. “There is no discussion on this point. The only things lying between us and you are the days, the nights and the battlefield,” Nasrallah added in a threat to Israel.

“I’m not saying we reserve the right to respond at the appropriate time and place,” said Nasrallah. “Absolutely not. We will respond. That’s final.”

Shukr was considered second only to Nasrallah in importance in Hezbollah, but the terror chief minimized the impact his assassination would have on the functioning of the organization.

“When one of our commanders becomes a martyr, he is swiftly replaced. We have an excellent new generation of commanders,” he said.

He further denied that military pressure on Hamas, Hezbollah or other Iran-backed groups would cause them to surrender.

“The aspiration of Benjamin Netanyahu is that Hamas will tell him: ‘Come, here are the hostages and the weapons.’ This will not happen. We will not surrender, neither in Gaza, nor in Lebanon, nor in Yemen.”

For his part, Netanyahu also celebrated Israel’s confirmation that it had killed Hamas military chief Muhammad Deif.

“Deif was responsible for the terrible massacre of October 7 and also for many murderous attacks against the citizens of Israel. He was Israel’s number one wanted man for years,” Netanyahu said at the end of a briefing by IDF Homefront Command chief Maj. Gen. Rafi Milo and Yoram Laredo, director of the National Emergency Management Authority.

Netanyahu declared that Deif’s elimination “reinforces a simple principle that we have established: Whoever hurts us, we hurt them.”

Israel has not taken credit for or officially commented on Haniyeh’s death. Iranian leaders have regardless vowed revenge against Israel and Netanyahu said on Wednesday night that there would be “challenging days ahead.”

Since October 8, Hezbollah-led forces have attacked Israeli communities and military posts along the border on a near-daily basis, with the group saying it is doing so to support Gaza amid the war there.

So far, the skirmishes have resulted in 25 civilian deaths on the Israeli side, as well as the deaths of 18 IDF soldiers and reservists. There have also been several attacks from Syria, without any injuries.

Hezbollah has named 385 members who have been killed by Israel during the ongoing skirmishes, mostly in Lebanon but some also in Syria. In Lebanon, another 68 operatives from other terror groups, a Lebanese soldier, and dozens of civilians have been killed.

Times of Israel staff contributed to this report.