The IDF said that "Operation Northern Shield" was initiated under a special task force that has since 2014 been leading operational, technological and intelligence efforts on the issue of tunnels on the northern border and has "developed vast abilities and knowledge on Hezbollah's attack tunnel project".
"The surprise component of that plan was supposed to be tunnels that would allow infiltrators into Israel", he said.
On Monday, Israeli Prime Minister Benjamin Netanyahu met U.S. Secretary of State Mike Pompeo in Brussels. A Lebanese army source said the situation was calm on its side of the border, as did United Nations peacekeepers operating there.
Israel's Foreign Ministry spokesman Emanuel Nahshon said Hezbollah is under the direction of Iran.
IDF officials estimated the operation would last for a few weeks, but a response from Hezbollah could prolong it further. Israel has not said whether it conducted the attack and Syrian state media did not identify who carried it out.More news: Apple implements Do Not Disturb app on iPhone, after TRAIs warning
Citing the Shehab News Agency, the Israeli news site quoted a senior Hezbollah official as saying, "We are closely monitoring the enemy's activities in the area".
It is unclear how many tunnels snake into Israeli territory from Lebanon, but the IDF stressed they were not operational and that work to expose them was taking place in Israeli territory and without crossing the border.
The area around the Israeli town of Metula has been declared a closed military zone, with the army distributing images of heavy machinery digging into the ground.
Israel has spent years dismantling a network of tunnels from the Gaza Strip into Israel, using several methods to destroy them and prevent them from being rebuilt.
"There is no immediate threat to Israeli citizens", Conricus said of the Lebanese front, noting that while the army has enhanced its presence in the north, it has not summoned reserve soldiers. Manelis said the Lebanese Armed Forces is not capable of controlling what occurs in southern Lebanon.More news: Oil prices surge on trade war truce, prospects for Russian output cuts
Netanyahu has pledged to stop Iran from entrenching itself militarily in Syria and to keep it from transferring advanced weapons to its ally Hezbollah in Lebanon.
Since then, Hezbollah has become one of the main supporting actors in the war in Syria and tensions with Israel have remained high. In recent years, Israel has destroyed dozens of tunnels dug by Hamas under their shared border.
Hezbollah is also a powerful political party in Lebanon.
Iran and the Iran-backed Lebanese group Hezbollah are major players in the war in Syria and their influence has alarmed Israel, which has repeatedly launched attacks on what it describes as Iranian and Iran-backed targets in the country.
Neither side appears interested in another full-fledged confrontation like the 2006 war, but any skirmish could spark an all-out conflict.More news: Ebola Outbreak Claim 19 Lives Within Five Days in DR Congo