Why Israel is considering a longer stay in Lebanon

Israel's reasons for staying in Lebanon are growing longer and longer by the day. And as time passes without a diplomatic - or a clear-cut military - solution to the conflict, Israel is becoming more and more influential in this country.

Many Lebanese and Palestinian analysts say Israel intends to hang onto the territory it overran last month indefinitely. They point to these factors as tipping the scale overwhelmingly away from early Israeli withdrawal:

* Syria's Arab League mandate for policing Lebanon expired July 27. Unless the mandate is renewed (an event considered not certain), Syria is now on the same footing as Israel in Lebanon: i.e., unauthorizedUFquoteEach day brings word of Israeli businessmen selling goods and services to the south Lebanese.

occupier. Israel can argue even more persuasively now that an Israeli withdrawal would be fair only if it coincided with a Syrian withdrawal.

* The Palestine Liberation Organization has done little in recent days to convince the world - or at any rate the United States government - that it has accepted the existence of the state of Israel. Israel thus, it seems, will be able to justify continuing to hold a cordon sanitaire in Lebanon to protect northern Israel from an organization that, Israel can continue to maintain, is out to liquidate the state of Israel.

* Israel's military casualties mount daily. In the long run this might cause the Israeli public to turn against the war on the PLO just as many Americans turned against the war in Vietnam (though the Israelis are decidedly more determined nationalists than the Americans of the 1960s). In the short run Israeli casualties in Lebanon will probably cause the government of Menachem Begin to feel it has paid too high a price to withdraw from Lebanon before it has ensured the neutralization of the PLO and the reordering of Lebanon to Israel's liking.

* Israel continues to expand its economic presence in the south Lebanon marketplace. Each day brings word of Israeli businessmen selling goods and services to the south Lebanese. An El Al (Israeli airlines) office has been established in Sidon. South Lebanese wholesalers are being encouraged to ship merchandise through the port of Haifa. Israeli produce is gaining a larger share of the market in Lebanon due to the devastation of south Lebanese agriculture.

* Israel's surrogates and allies still need the protective shield of the Israeli Army so that they can build up their political and military strength. This goes equally for Maj. Saad Haddad's south Lebanon militia, and for the Phalange, whose ambitious young leader, Bashir Gemayel, recently declared his candidacy for president of Lebanon. Major Haddad's militia controls western Lebanon from the Israeli border to Sidon, while the Phalange controls from Sidon to Byblos.

Israel still has to work out a control structure for the mountainous Shouf region, where competing Druze clans predominate. They seem highly reluctant to collaborate with the Israelis, Major Haddad, or the Phalangists.

While Israel has been entrenching itself in southern Lebanon, it has not resolved, either militarily or diplomatically, the problem of west Beirut. If the former is of paramount importance, then it may be in Israel's interest not to go into west Beirut. Instead, Israel might keep the city under indefinite siege, slowly encroach on it, and make life difficult for residents of west Beirut by cutting electricity and restricting movements as was the case July 27. Meanwhile, Israel could strengthen its position and that of its allies in the rest of Lebanon.

Nonetheless, Israeli military pressure on PLO-held west Beirut has intensified in recent days.

On July 27, Israeli jets dropped bombs on residential neighborhoods of west Beirut proper, an area they have mostly avoided hitting in the past. In one air raid, bombs destroyed an apartment complex less than a mile from the Hamra commercial district, killing 84 civilians, according to sources at the scene. It was the sixth straight day of Israeli bombing raids on the city and followed sustained overnight shelling.

PLO officials say they expect an Israeli attack soon to try to capture completely the international airport and the Burj Al Barajneh refugee camp.