Israel's Plane/Beirut, page-3

the USA & Lebanon has a defense agreement, which stops Lebanon enforcing its air space

US Department of Defense and the Lebanese Armed Forces (LAF)

A condition of the United States approving weaponry for the LAF is that it does not breach the US qualitative military edge (QME) policy, which commits the United States to helping maintain Israel’s military superiority against its neighbors and adversaries. For example, the United States has not provided air-defense systems to the LAF, as those could be used against Israeli Air Force jets and UAVs that breach Lebanese airspace on a near-daily basis on reconnaissance missions, or to launch airstrikes against targets in neighboring Syria.

https://www.atlanticcouncil.org/wp-...he_United_StatesLebanese_Armed_Forces_WEB.pdf