Israel announced on Tuesday the launch of a military operation aimed at "exposing and thwarting" Hezbollah tunnels stretching from Lebanon into northern Israel.
Occupation army spokesman Jonathan Conricus said the "attack tunnels" detected were not yet operational, noting that the Israeli operations would take place within the occupied Palestinian territory.
During Prime Minister Benjamin Netanyahu's meeting in Brussels on Monday with U.S. Secretary of State Mike Pompeo, the Secretary also emphasized America's commitment to Israel's national security and "absolute right to self defense".
The military did not disclose how many tunnels snake into Israeli territory from Lebanon or how long the operation would last.
"Whoever tries to harm Israel will pay a heavy price", Netanyahu said in a statement after returning to Israel early in the morning.More news: Meghan Markle ignores negative news, believes British press out to get her
It later published a photograph of a tunnel that it said it had uncovered.
Near the Lebanese village of Kfar Kila, an AFP photographer on Tuesday saw at least one Israeli bulldozer churning up earth, apparently as part of Operation Northern Shield.
"UNIFIL is working with all interlocutors in order to maintain the overall stability", she said.
"Army units deployed in the area are carrying out their usual missions along the border in cooperation and coordination with UNIFIL", it said.
Israel views the Iranian-backed Hezbollah and its vast weapons cache as a major threat.