One side aim of Israel's heavy attack in recent days on Palestine Liberation Organization positions in west Beirut is to speed the departure of the area's civilian population.
Maj. Gen. Amir Drori, Israeli chief of northern command, Aug. 3 advised civilians in west Beirut to leave the city for their own good. And Israeli forces advancing with tanks and bulldozers Wednesday, shouted in Arabic from loudspeakers: ''Run for your lives, clear the battle zone.''
Since the beginning of the siege of west Beirut, nearly two months ago, Israel has frequently urged civilians to leave the western sector. ''For weeks we have dropped pamphlets by air telling them to leave, used psychological tactics, and nothing worked,'' says one Israeli strategic expert. ''Now we are saying it right out - stay and you take the risk.''
Israeli officials believe the presence of a large civilian population in west Beirut encourages the PLO to believe that Israel will not directly assault the city because this would cause enormous civilian casualties. Israeli military estimates of civilians in west Beirut vary - this reporter was told 200,000 to 300,000 remain while the Jerusalem Post quoted Israeli military sources as citing 500,000.
Already, Israel has reaped harsh world criticism after attacks like last Sunday's massive air raid on west Beirut which killed between 70 and 238 civilians according to varying Lebanese sources. Lebanese radio said that the Aug. 4 heavy land and sea bombardments had killed and injured hundreds.
Israeli officials state bluntly that the tightening siege of west Beirut has been aimed at getting noncombatants to leave. During the siege Israel has frequently halted food, gasoline, electricity, and water supplies to the area. The blockage is now said by United Nations officials to hold the threat of epidemic. Asked about the water cutoff, one military source said, ''the purpose is to make life for everyone in there so difficult that it would induce the civilian population to leave while (we know) the PLO won't leave.''
Responding to the same query, a senior official said: ''We want the civilian population out of the city because the PLO is hiding behind it as a screen. Once west Beirut is cleared of civilians, the area can be attacked with less hesitation. This doesn't mean we want to attack, but it reduces the PLO's conviction that they have the bargaining option.''
So far, a large number of west Beirut residents have proven resistant to departure. While thousands have fled, others have stayed to protect their homes and businesses or simply because they have nowhere else to go.
The Israeli government believes the PLO will not accept a negotiated formula to leave Beirut without the application of military pressure. Sources here say the continued presence of civilians will not alone be sufficient to deter the military option if the PLO stays put.
For the moment Israeli strategy now seems to involve a slow and steady piecemeal seizure of PLO positions, rather than a full scale invasion of west Beirut. The fighting Aug. 4 on three fronts saw the Israelis take a piece of west Beirut territory 600 meters long and 60 meters wide just across a strategic dividing line between the eastern and western sectors. It left the Israelis in postion to seize a main road dividing west Beirut proper from Palestinian refugee camps and strongholds to the south.