The presence of security officials on board Israeli flights and surrounding their takeoffs and landings has gone up in recent days in the wake of Hezbollah's promise to retaliate against Mugniyeh's February death, Ynetnews reported Friday.

"The threat is extremely concrete, and there is no choice but to do everything possible," an aviation security force said.

Shin Bet protection forces decide the amount of security needed on Israeli flights depending on daily risk levels. Security demands reportedly may differ from day to day depending on intelligence findings.

The airlines' main concern reportedly is that a passenger flight will be targeted by missiles during landing or takeoff, especially because no Israeli planes have systems to deflect such attacks.

"We are fully coordinated with the authorities in each country, and receive full cooperation," an aviation security source said.