Israeli Prime Minister Benjamin Netanyahu is warning that anyone who tries to attack Israel "will pay a heavy price".
Israel said on Tuesday it had launched an operation to "expose and thwart" cross-border attack tunnels from Lebanon dug by the Iran-backed movement Hezbollah and that their goal was to send militants to attack Israel.
"We see Hezbollah's activities as a flagrant and blatant violation of Israeli sovereignty" and United Nations resolutions, said Lt. Col. Jonathan Conricus, a military spokesman.
Israeli military personnel and a drill are seen as they work next to the border with Lebanon, near Metulla, northern Israel December 4, 2018.
It is in this context that Israel was able to successful take tunnel detection technology from the Gazan border, where it was used to discover and destroy one Hamas tunnel after another, and bring it to the Lebanese border. The Israel Defense Forces embarked on Operation Northern Shield on Tuesday, surprising observers on both sides of the border.
"We are acting with determination to prevent Iran from being rooted in Syria. we are also acting against Iran's terrorist actions in Lebanon", he said.
Israeli officials have long warned the threat posed by Gaza's Hamas rulers pales in comparison to that of Lebanon's Iran-backed Hezbollah - a heavily-armed mini-army with valuable combat experience and an arsenal of some 150,000 rockets that can reach almost every part of Israel. The operation would yield a propaganda victory picture that the organization's leadership could use to demoralize Israel. In recent years, Israel has destroyed dozens of tunnels dug by Hamas under their shared border.
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The tunnel is said to be 200 meters (656 feet) in length, with 40 meters (131 feet) inside Israel.
In a telephone briefing with The Israel Project (TIP), reserve Col. Atai Shelach, former commander of the Yahalom unit in charge of dismantling tunnels, said it was just a matter of time before Israel would launch such an operation. A small explosion scared him away and the tunnel was later blown up with a more powerful blast.
Additionally, the Lebanese army command said that it is watching the situation closely, reiterating its readiness to confront any emergency situation.
Israel and Hezbollah fought a monthlong war in 2006 that ended in a stalemate.
Yoav Kish, a member of Netanyahu's party and chairman of the Knesset's Internal Affairs Committee, said the latest operation proves that what was seen as the prime minister being "hesitant and weak" in Gaza was actually "restraint" that made the move in the north possible. He took over the defense portfolio from his resigning minister and promised to pursue a hard line against Israel's enemies during what he described as a "complex" security situation. Israel has also reportedly carried out killings against Hezbollah figures.
Neither side appears interested quite yet in another full-fledged confrontation like the 2006 war, but any skirmish could spark an all-out conflict along the tense border.