Israel is quietly pursuing contacts with Lebanon on forming a special south Lebanese army force to facilitate a pullback of Israeli troops, well-placed sources here have disclosed.
The plan is still a long way from fruition. It could be fatally undermined by any major opposition from the south's majority Shiite Muslim community, or from the neighboring Arab state of Syria.
The Israelis, for their part, seem to feel increasingly hard pressed in south Lebanon since the suicide bomb attack Nov. 4 on their headquarters in the coastal city of Tyre. The south Lebanon morass, for occupier and occupied alike, is becoming ever more messy.
Lebanon is understood to have agreed to the talks and a special ''territorial'' Army brigrade only after considerable reflection, since the force was foreseen in a May 1983, US-mediated peace accord with Israel.
The Beirut government has been under pressure to repudiate this accord. Syria has been in the forefront of opposition, arguing it would legitimize Israel's summer 1982 invasion and occupation of roughly half of Lebanon.
Beirut is said to have decided to go ahead with the talks out of fear that, otherwise, Israeli troops would unilaterally pull back without leaving any authority sufficiently strong to head off sectarian violence.
Fierce fighting followed a similar Israeli redeployment in September away from the Shouf mountain area southeast of Beirut. Some Lebanese officials charge Israel, in a policy of divide and conquer while occupying the Shouf, had fanned hostility between the area's Druze and Christian populations, thus helping ensure trouble after the troop pullout.
In the past week or so, Israeli troops have effected several minor changes in their positions in south Lebanon - a move seen partly as a ''threat that if we drag our feet, we could face 'another Shouf,' '' in the words of a south Lebanese official.
Lebanese sources vary on when contacts concerning the territorial brigrade began, but suggest they entered a more active phase a few weeks ago. This would be shortly after the bomb attack on Israeli headquarters in Tyre.
The talks primarily involve Army officers on both sides. But various internal Lebanese parties and rival religious communities have either been consulted or have otherwise kept informed of the process.
There has been no public announcement of the contacts.
Ideally, the talks are said to seek a ''territorial brigade'' of men living in south Lebanon, assembled from the regular Lebanese Army and various rival religious and political militia factions in the south.
Under the May agreement, the brigade would control the southernmost 20 miles or so of Lebanon, after Israeli withdrawal. Yet Lebanese sources say Israel may soon hope that it instead take over a strip further north at first, facilitating the first in a series of piecemeal Israeli withdrawals.
The contacts have reached at least sufficient detail, Beirut sources say, to have settled on a tentative commander for an eventual territorial force: a Col. Elias Khalil, a Christian career officer from the southern village of Mardoucheh.
But among key issues still reportedly not resolved is the role of the main Shiite force, Amal, in such an arrangement. The Israelis are said to want the ''territorial brigade'' to draw on Shiites from individual village militia groups Israel has helped implant since the invasion. The Lebanese are convinced that any workable arrangement must have Amal approval, even if Amal does not participate directly.
Amal's own dilemma much resembles that of Lebanese President Amin Gemayel's government, and of many ordinary south Lebanese civilians: how to avoid excessive cooperation with an occupying Israeli foe, but at the same time do everything possible to speed an orderly withdrawal of the Israeli Army and a return to Lebanese rule.
Amal sources interviewed in south Lebanon suggest the Shiite group is determined to oppose the ''territorial brigrade'' as it seems to be shaping up - first, because Colonel Khalil is ''unacceptable'' as a commander, and second, and any such brigrade in the sources' view must be set up after only the Israelis withdraw.
Since the November bomb attack, south Lebanon - postcard-beautiful in unseasonably warm Mediterranean sun - has become politically ugly for all sides.
The Israelis have slowly, surely reduced their profile. More of their troops huddle along the Awali River. Patrols are fewer and better fortified.
Meanwhile, Israel has imposed licensing requirements on all motor traffic between south Lebanon and the rest of the country. The result: a huge line of supply trucks, as long as two miles, at the Awali bridge crossing from the north. Some drivers wait as long as four or five days.
''Look inside!'' pleaded one driver, pointing toward the back of his truck, where fly-bitten cattle shifted restlessly in the midmorning sun. ''I have been here for more than two days. The young calf is dead.''
An Israeli spokesman in Sidon said, ''I will not at all minimize'' the problems the new restrictions have caused for the local population, nor the rising resentment against the Israelis among even south Lebanese who previously maintained a carefully indifferent stance.
The spokesman said the restrictions were the result of a difficult balancing of various considerations, including the effect on local citizens. ''But one of our supreme needs is to protect our own population here,'' he said.
Amal has inevitably similar concerns for its own Shiite population. Though generally committed to reestablishing legimitate Lebanese government authority in the south, Amal must also consider growing extremist pressure from other Shiites, particularly young and pro-Iranian ones in the south. It is such militants whom the United States, France, and Israel have accused of complicity in separate suicide bomb strikes against their headquarters in recent weeks.
At a Shiite gathering in Sidon a few days ago, alongside relatively moderate Amal followers were representatives of a tougher line. A wall poster read: ''Death to France. Death to America. Death to Israel. . . .''
Amal's relative moderates say they still feel the south's Shiites generally support them. But as one figure remarked, if ''the present situation (of Israeli occupation) continues, that could change.''