Domestic pressure is mounting inside Israel for a partial pullback of Israeli troops in Lebanon to halt mounting casualties there. But Israeli military analysts, including Israel's defense minister, Moshe Arens, believe such a move will not be easy politically or militarily.
Five Cabinet ministers - ranging from extreme hawks to relative moderates - this week urged Defense Minister Arens to speedily submit detailed plans for Israeli troop redeployment in Lebanon for discussion by the Ministerial Defense Committee.
In the near future the entire Cabinet will discuss the security situation in Lebanon and the possibilities for redeployment, according to Deputy Foreign Minister Yehuda Ben-Meir. Commenting on unconfirmed Israeli press reports today that Israel's prime minister, defense minister, and foreign minister had already agreed to a partial pullback within the next several weeks, Mr. Ben-Meir insisted that such a decision would have to be taken by the full Cabinet.
Israeli newspapers have reported that several alternative military redeployment plans already exist, with the chief difference being how far south the Israeli Defense Forces would withdraw on the Lebanese coastal road. All the plans are said to envision pulling out of the mountainous Shouf region in central Lebanon where Israel has taken heavy casualties, while maintaining strategic points on the Barouk and Hermon peaks.
The opposition Labor Party has called for a speedy partial pullback to be followed by a total unilateral Israeli pullback within three months.
Mr. Arens says the Israeli government will coordinate any move on troop redeployment with the United States and Lebanon. Should no progress occur with the Syrians prior to Prime Minister Menachem Begin's expected trip to the US in July, the subject of redeployment will undoubtedly be high on his agenda for talks with President Ronald Reagan. But Mr. Arens acknowledged that the government will have to find the strength to withstand both foreign and domestic pressure in order to obtain its aim in Lebanon.
In making their decision, however, Israeli political leaders will be confronted by a contradictory set of considerations typical of the confusing and complex Lebanese scene.
A prime consideration will be maintaining the newly mended and currently excellent relations with the US. The US still maintains that Syria will ultimately modify its current veto of the Israel-Lebanon accord on Israeli troop withdrawals from Lebanon, and will agree to a parallel Syrian troop pullback from Lebanon.
As the Lebanese parliament finally debates ratification of this accord, Syria has indicated it may be willing to receive US Secretary of State George Shultz (though not to discuss its veto) and Radio Monte Carlo, whose Damascus correspondent is often used for selective leaks by Syrian authorities, has issued an unconfirmed report that Syrian Foreign Minister Abdul Halim Khaddam may visit Washington, D.C.
However, informed Syria watchers here, both in and out of government, remain skeptical and divided over what they believe to be Syria's ultimate aims. And in deciding on whether to pull troops back, the Israeli government must grapple with other considerations beside US approval.
''Israel must maintain at all costs two minimal objectives in Lebanon,'' said (ret.) Col. Yaacov Heichal, research fellow and expert on Israeli military strategy at the Jaffe Center for Strategic Studies of Tel Aviv University. ''The first is to keep the peace in Galilee (meaning to keep southern Lebanon free of hostile elements who might shell Israel's northern region). The second is to minimize the number of casualties incurred by our soldiers there.''
But, as Defense Minister Arens stressed to the Israeli Cabinet, a partial pullback will not necessarily guarantee those goals - unless an international force or the rebuilt Lebanese Army moves into abandoned Israeli positions. ''What we want to be sure of,'' Mr. Arens told Israel radio, ''is that when we redeploy we don't leave behind a vacuum that can be filled by PLO terrorists and the Syrian Army. If we do that, then all we will have achieved is simply moving the line where terrorist operations occur closer and closer to the Israeli border.''
To fill this vacuum, however, Israel would need the cooperation of both the US and Lebanon. But both currently oppose a partial Israeli withdrawl lest it remove Syria's incentive to join the negotiating process. Moreover, Israeli leaders do not believe that the Lebanese Army is ready to step into the Shouf and maintain order there.