As Washington attempts a diplomatic Hail Mary pass, pushing for a Lebanon cease-fire before the presidential election, the newly-installed Hezbollah chief, Naim Qassem, is threatening to intensify the war even as the Israel Defense Force methodically dismantles the terror group’s capabilities.  

Addressing the American ambassador at Beirut, Lisa Johnson, on Wednesday, Mr. Qassem boasted in his first speech as Hezbollah secretary general that “neither you nor those with you will see the defeat of the resistance, even in dreams.” 

The Iran-trained cleric vowed to keep striving for the goals of his late predecessor, Hassan Nasrallah, and his Tehran benefactors, including the destruction of the Jewish state. At the same time, two White House envoys, Amos Hochstein and Bernard McGurk, are scheduled to arrive in Israel Thursday with a new diplomatic initiative.

The proposal reportedly contains a 60-day cease-fire, during which new border arrangements would be set for the Lebanese border under American guarantees. Israeli officials are signaling a readiness to accept war-ending agreements with Beirut.

Yet disagreements remain, and Israel is striving to reach any pact from a position of strength. “We will hold negotiations only under fire,” Defense Minister Yoav Gallant said Wednesday as the IDF widened its assault on Hezbollah assets, hitting new targets beyond southern Lebanon and Beirut.    

Mr. Qassem, who is widely dismissed as a figurehead and who lacks Nasrallah’s charisma and strategic capabilities, did not dismiss the idea of diplomacy. “We will agree to cease only if the other side ends the aggression, and only under our conditions,” he said.

The new Hezbollah chief was officially named as secretary general after a more likely heir, Hashem Saffieadin, was eliminated by Israel earlier this month. On Wednesday the IDF announced the killing of Mustafa Ahmad Shahdi. He had replaced the commander of Hezbollah’s elite Radwan force, Ibrahim Aqil, who was killed on October 20.   

Is the new Hezbollah chief next? “Temporary appointment. Not for long,” Mr. Gallant wrote on X over Mr. Qassem’s picture this week. In his Wednesday speech, Mr. Qassem answered by threatening to kill Prime Minister Netanyahu. 

Mr. Netnayahu “died of fear from the drone that we used to attack his house,” Mr. Qassem said Wednesday, referring to an October 19 attack on the premier’s private home at Caesarea. “This time, Netanyahu was saved. We don’t know when he will die, but some Israeli may kill him. He might die during one of his speeches.”

As Mr. Qassem speechified, his televised feed on Hezbollah’s al Manar network was briefly cut off in what might have been a cyber attack. Shortly before the speech started, the IDF Spokesman in Arabic, Avichai Adraee, warned residents of Baalbek, a city on the Lebanese-Syrian border, to evacuate.

The ensued air attack on Baalbek targeted crossings Iran uses to resupply Hezbollah with rockets and missiles. According to Mr. Gallant at least 20 percent of that arsenal has been destroyed in the last few weeks. IDF infantry troops, meanwhile, are demolishing Hezbollah infrastructure in southern Lebanon.

“The slow movement progress on the ground is due to the fact that every building, every tunnel, and every village needs to disappear,” a Beirut-based analyst, Georges Hadad, writes on X. “All infrastructure that can be used by Hezbollah will need to be rebuilt, and this will take years.”

Hezbollah is now increasingly relying on explosive-laden drones, which are less costly than rockets and missiles, and are also more likely to elude Israel’s aerial defenses. On Wednesday numerous towns and cities in northern Israel were under alert as one or more drone infiltration was suspected. 

“The current situation could necessitate an intensification of the Israeli offensive in southern Lebanon,” the founder of the north Israel-based Alma research center, Sarit Zehavi, says. “This will require patience and likely take a few more weeks.”

Messrs. McGurk and Hochstein hastily attempt to set up an international force to augment the current United Nations force. Since 2006, that force and the Lebanese army have failed to prevent Hezbollah’s arming on Israel’s border.

A post-war agreement must be “an effective political arrangement that does not leave Hezbollah free to rebuild its terror army, and it must come with an effective enforcement mechanism,” Ms. Zehavi says. 

Israel insists that the IDF would be able to enter southern Lebanon at any time that it detects a Hezbollah attempt to return to the area. Such a demand is likely to emerge as a stumbling block to Washington’s diplomatic efforts in the waning days of President Biden’s tenure.

“We in northern Israel have staying power as the IDF degrades Hezbollah,” Ms. Zehavi says. “What is important going forward is to translate these military achievements into a new reality that does not allow Hezbollah to again exploit cease-fires in order to build monstrous threats.”