The operation was announced by the Israeli military on Twitter on Tuesday.
Israeli military spokesman Lieutenant Colonel Jonathan Conricus told Reuters news agency that the operation would only take place on Israel’s side of the border and that it would not extend into Lebanon.
“We see the Hezbollah activities as a flagrant and blatant violation of Israeli authority,” he told Reuters.
In a tweet, Israeli military spokesperson Avichay Adraee said the Lebanese government is responsible for the build-up of the tunnels, saying they are endangering Lebanese citizens.
Also on Tuesday, Israeli Prime Minister Benjamin Netanyahu said his country would continue to take action to ensure the “security of Israel”.
“Whoever tries to attack the State of Israel will pay a heavy price,” Netanyahu said in a statement.
“We will continue with additional actions – open and covert – in order to ensure the security of Israel.”
Hezbollah has not responded to the military operation yet, but the UN mission near the Israel-Lebanon border, UNIFIL, said in a statement it was notified of the operation on Tuesday morning.
“The overall situation in UNIFIL’s area of operation remains calm and UNIFIL is working with all interlocutors in order to maintain the overall stability,” the statement said.
“UNIFIL peacekeepers have further increased their patrolling along the Blue Line, together with the Lebanese Armed Forces (LAF), to maintain the overall stability and avoid misunderstandings that could lead to any escalation,” the statement added.
Lebanese online news portal Tayyar reported that the Israeli army was excavating areas opposite the Lebanese villages of Kfarkela and Adaisseh on the southern border.
According to Al Jazeera correspondent Natasha Ghoneim, the operation by Israel is a rare occurrence.
“Israeli military spokespeople are saying they have discovered tunnels made by Hezbollah and that they are attempting to thwart any attack from Hezbollah from Lebanon into Israel,” Ghoneim said from West Jerusalem.
“Since Hezbollah had its war with Israel in 2006, we haven’t seen this kind of operation in the north as there has been a tense detente between Hezbollah and Israel,” she added.
Last night, the Israeli prime minister travelled to Brussels unexpectedly to talk to US Secretary of State Mike Pompeo, briefing him on the operation that started on Tuesday morning.
“The timing is important as well, because three days ago Israeli police have recommended that Israeli Prime Minister Benjamin Netanyahu be indicted on charges of corruption that have been plaguing him,” Ghoneim said.
She added that although Netanyahu has remained popular, those that are sceptical of this operation say this could be an effort by him to divert attention away from those legal problems.
Later on Tuesday, the White House announced its support for the Israeli operation.
President Donald Trump’s national security advisor John Bolton said that “the US strongly supports Israel’s efforts to defend its sovereignty.”
“More broadly, we call on Iran and all of its agents to stop their regional aggression and provocation, which pose an unacceptable threat to Israeli and regional security,” Bolton said.
In 2006, Hezbollah and Israel fought out a war in the border region in which more than 1,100 Lebanese, mostly civilians, and 159 Israelis, were killed.
During that war, the armed Shia group was able to overwhelm Israel’s ground invasion of southern Lebanon and attack military and civilian targets, undermining internal Israeli support for the war and spurring regional support for Hezbollah’s military successes against a state army.
Over the course of that war, Israel has targeted alleged Syrian and Hezbollah arms convoys on multiple occasions in an attempt to block any Iranian efforts to transfer weapons to the group.
Since the start of the Syrian war, more than 200 attacks were carried out by Israel, according to its military.
Israel has accused Iran of supporting Hezbollah with money and arms to continue fighting in Syria and retain its power in Lebanon.