IDF troops uncovered a third Hezbollah tunnel that crosses the Blue Line from Lebanese territory into Israel on Tuesday, while Prime Minister Benjamin Netanyahu warned Hezbollah of an "unimaginable blow" if it chooses to retaliate.
"The attack tunnel is under the IDF's control and does not pose an imminent threat," the army said.
The IDF placed explosive devices inside the tunnel. "Any entrance from the Lebanese side is dangerous," the IDF stressed.
The Israeli military said it held the Lebanese government responsible for the attack tunnels dug from its territory.
"This is another blatant breach of UN Resolution 1701 and of Israeli sovereignty," the IDF accused.
"IDF troops will continue to operate in accordance with the approved plan to locate and expose the Hezbollah terror organization's attack tunnels."
Hezbollah, Lebanon's most powerful armed group, dug the tunnels under the border with the aim of launching attacks into Israeli territory with backing from its regional sponsor Iran. Hezbollah has yet to comment.
Prime Minister Netanyahu visited the northern border on Tuesday afternoon and issued a warning to Hezbollah: "If they make the mistake of choosing to harm us, they will sustain an unimaginable blow."
During his visit to the border, Netanyahu met with the GOC Northern Command and other senior commanders, as well as with soldiers taking part in Operation Northern Shield and the heads of the local authorities in the area.
"I just finished a comprehensive discussion with the IDF chief, the GOC Northern Command and the commanders, and I'm impressed by the spirit of the troops," he told reporters. "There are results here. We just exposed the third tunnel, but the most impressive thing is the readiness—both physically and mentally—to a very strong response should Hezbollah make the great mistake of harming us in some way or opposing our operations."
"Hezbollah thought it was digging... but we knew and planned carefully. It didn't leak, we kept the secret," the prime minister added. "We're carrying out exactly what we planned, but we're also prepared for unplanned things, and there's great firepower here."
Netanyahu explained that if the IDF hadn't uncovered the tunnels, Hezbollah would have been able to carry out a killing spree in communities in northern Israel. "Hezbollah could have gone into a killing spree and abductions inside your communities," he told local authority heads. "Including cutting off roads and everything else."
Also on Tuesday, Lebanese President Michel Aoun said he saw no risk to peace from Israel's Operation Northern Shield.
"We certainly took this issue seriously—the presence of tunnels at the border—and Israel informed us via the United States that it does not have aggressive intentions and it will continue to work on its (territory)," Aoun said.
"We also do not have aggressive intentions, and so there is no danger to peace in this (Israeli) operation...We are ready to remove the causes of the dispute, but after we obtain a final report and we set out the matters that need to be dealt with," he told a news conference alongside his visiting Austrian counterpart.
The head of the UN peacekeeping force in Lebanon, UNIFIL, said a UNIFIL technical team had verified the existence of a second tunnel. The peacekeepers last week confirmed the presence of one near the Israeli town of Metula.
Maj. Gen. Stefano Del Col, in a statement issued after meetings with Aoun and Parliament Speaker Nabih Berri, said the matter was "serious."
UNIFIL was making "every effort to maintain clear and credible channels of communication with both sides so that there is no room for misunderstanding on this sensitive matter."
Israel has said it is up to UNIFIL to deal with the tunnels on the Lebanese side of the border.
Aoun, a political ally of Hezbollah, said in a separate statement that Lebanon was committed to the implementation of UN Security Council resolution 1701, which ended the last war between Hezbollah and Israel.
Earlier Tuesday, Hezbollah released a video of an IDF robot operating near the tunnel stretching from Kafr Kela into Israel. The video shows one of the soldiers pulling the robot out of an opening in the ground with a rope.
Hezbollah's videos, photos and constant reports of IDF works revealed a new work site near the village of Blida in Lebanon, where the terror group says the Israeli army started digging and searching for tunnels.
Reuters contributed to this story.