Saudi Arabia and Iran have offered apparently competing aid packages to Lebanon’s small and modestly armed military as it confronts increasing attacks at home by militants with ties to extremists fighting in Syria’s civil war.

The pledges total billions of dollars’ worth of mostly light arms and underscore the mounting concern of the Persian Gulf foes about the stability of a country where both have invested significant resources.

The aid is on top of the more than $1 billion spent by the United States since 2006 to train and equip the 65,000-member military, which has limited authority and yields to Iran-backed Hezbollah, Lebanon’s powerful Shiite militia. Hezbollah supports Syrian President Bashar al-Assad in his fight against Saudi-backed rebels. […]