Confirming a Friday night sortie in Syria, Netanyahu said Israel's air force had "struck Iran's warehouses, containing Iranian arms, in Damascus global airport".
"The accumulation of recent attacks shows that we're more determined than ever to act against Iran in Syria, just as we promised", the prime minister's office said. He added that Hezbollah retained underground facilities on the Lebanese side.
Lt Col Jonathan Conricus said the final tunnel was the largest one discovered so far - running hundreds of metres from underneath a Lebanese home and deep into Israeli territory.
Netanyahu also cited an Israeli search-and-dismantle mission against suspected Hezbollah attack tunnels along the border with Lebanon that was launched in December and deemed completed on Sunday.
Lt Gen Conricus said the latest tunnel originated from the Lebanese border town of Ramyeh.
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Investigators refused to confirm that amount but said they advised the family not to pay the purported kidnappers. Hagen's wife disappeared suddenly from the family's Lørenskog home on October 31st, and hasn't been seen since.
Israel has struck Iranian, Hezbollah and Syrian targets in the neighbouring state on dozens of occasions, although Tel Aviv rarely admits openly to carryout out specific attacks.
The tunnel wasn't operational or a threat to Israel's citizens, Israel's military says.
The highly publicised Israeli operation to expose and destroy the tunnels has gone ahead without drawing a military response from Hezbollah.
He also reiterated that Israel holds the Lebanese government accountable "for any act of violence or violation of 1701", the United Nations resolution that ended the 2006 war between Israel and Hezbollah. Israel, coordinating with United Nations peacekeepers in Lebanon, said it sought no escalation.
Netanyahu has vowed to intensify Israeli action in the wake of the United States' withdrawal.
But with that civil war winding down, Israeli security officials fear Hezbollah is refocusing its attention on Israel.