From “Wikipedia”:http://en.wikipedia.org/wiki/Lebanese_Civil_War#Israel_plans_for_attack:

In August, Israeli prime min­is­ter Men­achem Begin was re-elected, and in Sep­tem­ber, Begin and his defense min­is­ter Ariel Sharon began to lay plans for a sec­ond inva­sion of Lebanon for the pur­pose of dri­ving out the PLO. Sharon’s inten­tion was to “destroy the PLO mil­i­tary infra­struc­ture and, if pos­si­ble, the PLO lead­er­ship itself; this would mean attack­ing West Beirut, where the PLO head­quar­ters and com­mand bunkers were located” (Smith, op. cit., p. 377).

Now:

In March, Israeli prime min­is­ter Ehud Olmert was elected, and in July, Olmert and his defense min­is­ter Amir Peretz began to lay plans for a third inva­sion of Lebanon for the pur­pose of dri­ving out Hezbol­lah. Peretz’s inten­tion was to destroy the Hezbol­lah mil­i­tary infra­struc­ture and, if pos­si­ble, the Hezbol­lah lead­er­ship itself; this would mean attack­ing South Beirut, where the Hezbol­lah head­quar­ters and com­mand bunkers were located.