“The enemy transgressed all boundaries and redlines,” Nasrallah said in a widely anticipated speech Thursday evening local time about the attacks, which he described as “a major assault on Lebanon, its security and sovereignty, a war crime — an act of war,” and he said the attacks dealt an “unprecedented blow” to Hezbollah and Lebanon.

More than 30 people were killed on Tuesday and Wednesday across Lebanon when various Hezbollah hand-held devices, including pagers and walkie-talkies, exploded. The act of sabotage, presumed to be from the Israelis, left roughly 3,000 people injured. U.S. officials publicly denied any involvement in the attack and declined to directly attribute the attack to Israel.

Israel not only managed to sabotage the devices Hezbollah uses, but they set up an elaborate scheme to manufacture them through various shell companies that Israeli intelligence actually created, according to the New York Times. They had some real clients, and Hezbollah. The pagers made for Hezbollah contained batteries laced with the explosive PETN, per the Times.

Shortly before Nasrallah spoke on Thursday, the Israeli military announced it had begun airstrikes against targets in southern Lebanon.

“The IDF is currently striking Hezbollah targets in Lebanon to degrade Hezbollah’s terrorist capabilities and infrastructure,” the IDF said. “For decades, Hezbollah has weaponized civilian homes, dug tunnels beneath them and used civilians as human shields—having turned southern Lebanon into a war zone.”

LTG Herzi Halevi, the chief of the general staff of the IDF, approved plans for operations in the northern part of the country against Hezbollah, the military said on Thursday.

Israel’s purported actions this week present a potentially new chapter in the conflict between Israel and Hezbollah, which dates back several decades, though was reignited following Hamas’s Oct. 7 terrorist attack against Israel.

While Israel’s military carried out a ground invasion of Gaza in the aftermath of the Oct. 7 attack — which left roughly 1,200 people dead and 250 others who were kidnapped and brought back to Gaza — it was drawn into a cross-border narrow conflict with Hezbollah. Israel and Hezbollah began firing rockets and missiles from northern Israel into southern Lebanon and vice versa.

Amid concerns that Hezbollah could carry out a cross-border assault similar to Hamas, Israel opted to evacuate tens of thousands of civilians from their homes in northern Israel, and they remain displaced from their homes. Israeli leaders have cited getting those civilians back in their homes as a priority for their operations against Hezbollah.

Israeli Defense Minister Yoav Gallant warned on Wednesday, “We are at the start of a new phase in the war — we are allocating resources and forces to the northern arena,” though he did not clarify as to what the new phase would include.

Gallant spoke with U.S. Secretary of Defense Lloyd Austin on Wednesday in which the Israeli leader said they “reflect[ed] on the strategic, regional picture and to brief the Secretary on IDF operations in the southern and northern arenas, focusing on Israel’s defense against Hezbollah threats.”

There have been several moments since the fighting broke out where it appeared like Israel and Hezbollah’s limited conflict would escalate into an all-out war, though both sides have seemingly gone to great lengths to continue their fight without crossing that rubicon.

In late July, a Hezbollah rocket killed twelve teenagers in the Golan Heights, and days later, the Israelis carried out an audacious strike in Beirut targeting the senior leader, Fuad Shukr, whom it said was responsible for the deadly strike days earlier. Just a day after Shukr’s assassination, Israel is believed to have carried out another assassination against Ismail Haniyeh, a senior Hamas leader, in Tehran.

In the aftermath of both assassinations, Iran and Hezbollah made moves to retaliate and vowed to do so. Austin deployed more U.S. forces and resources to the Middle East to aid Israel in the event of a large response.

In late August, Israel carried out dozens of airstrikes across Lebanon at Hezbollah targets in what they described as “preemptive” strikes to prevent an attack, while Hezbollah proceeded to fire hundreds of rockets and drones at Israel, though Israel’s air defenses largely prevented casualties and damage.