Israel is becoming increasingly anxious about the fate of UNIFIL if Hizbullah increases its power in upcoming parliamentary elections in Lebanon.
Defense officials have also expressed concern with American plans to supply advanced military platforms to the Lebanese armed forces.
The Lebanese people will head to polls on June 7 amid predictions that Hizbullah will bolster its position in parliament and form the next coalition.
Israel is concerned that if Hizbullah wins the elections, some European members of UNIFIL will consider downsizing their participation in the force or completely withdrawing their personnel. Poland has already decided to withdraw its forces and transfer them to Afghanistan.
The concern also stems from the scheduled resignation of UNIFIL Command Maj.-Gen. Claudio Graziano, of Italy, and the handover of command of the 12,000-man force to the Spanish military, defense officials said.
"We are hoping to receive assurances that European countries will remain committed to UNIFIL even in the event of a Hizbullah victory in the elections," a senior defense official familiar with the issue said.
On Tuesday, IDF Chief of General Staff Lt.-Gen. Gabi Ashkenazi told the Knesset's Foreign Affairs and Defense Committee that while Hizbullah was amassing unprecedented amounts of weaponry, UNIFIL's presence in southern Lebanon was "making the task more difficult."
Senior defense officials said they were concerned with the supply of American arms platforms to Lebanon and warned that if Hizbullah formed the next government, the weapons would fall into the guerrilla group's hands.
Lebanese Defense Minister Elias Murr was quoted as saying last week that the US has promised to supply dozens of fighter jets, helicopters, tanks and unmanned aerial vehicles following the elections and regardless of its results.
Defense Minister Ehud Barak warned this week that if Hizbullah gained considerably in the elections Israel would not feel the restraints it did in 2006 about attacking Lebanese infrastructure.
"Today Hizbullah controls a third of the Lebanese government," Barak said. "If in the upcoming elections Hizbullah will gain more power in the government, that will open it up more than in the past to the IDF's force, and will give us a freedom of action that we did not have completely in July 2006."
During the early days of the Second Lebanon War in 2006, there was a debate inside the government about the degree to which the IDF should hit essential infrastructure in Lebanon, with much of the world urging Israeli restraint so as not to weaken the position of pro-Western Lebanese Prime Minister Fuad Saniora.
"The UN investigation will apparently find Hizbullah responsible for the killing of [former Lebanese prime minister Rafik] Hariri," Barak said, adding that this is a further indictment against Hizbullah for trying to undermine the legitimacy of moderate regimes in the region.