UN forces in Lebanon dig in against an array of 'foes'

In the bleached-dry, craggy terrain of southern Lebanon, a handful of Italians recently planted a rose garden, surrounding it with a permanent, elevated rock-and-concrete stone wall.

Nearby, a group of Frenchmen transplanted geraniums in the front of their beige prefab row ''homes.''

''We made the decision late in the season, but next year, it will be really beautiful . . . bellissimo,'' boasted one of the gardeners, who doubles as a captain in the United Nations forces stationed here.

The quasi-permanence of the United Nations Interim Force in Lebanon (UNIFIL) is rarely discussed in their isolated headquarters here. But the de facto status of the 6,000 troops from 11 nations is evident at every turn, from the more than 100 prefabs that have replaced tents to the plans for installing permanent telephone and water lines.

UNIFIL was deployed here in 1978 on a six-month assignment that has been extended every six months since then. And few of the forces have much hope that their peace-keeping mission will end in the near future.

At the troops' mess - recently decorated with green and white drapes - soldiers from Ghana, Nepal, Senegal, Ireland, Italy, Norway, Sweden, Fiji, the Netherlands, Nigeria, and France talk about which ''old friends'' will be returning on rotation next year. Many of the tall, proud Fijians are already on their second or third tours.

It is one of the nastiest of rough UN assignments. Seventy troops have been killed by the two sides they are trying to keep apart: the Palestinians with their hodgepodge of leftist Lebanese allies to the north, and the Israeli-backed rightist forces of Maj. Saad Haddad to the south.

Only last week Lebanese right-wing militiamen blew up a water pipeline and blocked roads leading into the UN's Naqurah headquarters here following the deaths of three militiamen, who were killed by a landmine Nov. 13. Major Haddad said Palestinian guerrillas had planted the mine and he charged the UNIFIL forces with negligence in failing to stop the guerrillas. The blockade was lifted Nov. 19.

Other critics claim UNIFIL has failed too. Its threefold charge was overseeing an Israeli withdrawal from Lebanon, preventing further hostilities, and helping the Lebanese government restore its authority in the south.

Instead, the Israelis flaunt their presence, a heavy stream of trucks and military vehicles crossing the Israeli border that has technically been closed for 33 years and driving past UNIFIL posts with equipment to help Major Haddad fortify his positions.

At the same time, UNIFIL should not be underrated. Its buffer zone of eight encampments and the environs, now considered the most secure area in Lebanon, have been transformed from an abandoned slice of territory to a strip of real estate much in demand by a population of 200,000.

Most important is the slow progress UNIFIL has made in bringing the Lebanese Army back to the area, now at a strength of 1,400, to share the duties of roadblocks, observation posts, and patrols.

''We are buying time until Lebanon can put its house in shape and eventually take over our jobs,'' an Irish officer said. ''It is working, but like their government, they aren't yet confident about the job.''

This development, plus the results of the July 24 US-orchestrated cease-fire that ended the latest round of hostilities, have led to cautious optimism here.

The underarmed UNIFIL personnel, outnumbered at least 4 to 1 by the bewildering array of opposition forces, are also hopeful that the mission of US special envoy Philip C. Habib later this month will bring progress in defusing tension in this most volatile of Middle East regions.

The need for intervention by outside governments reflects the basic problem for UNIFIL: Its mandate is one of merely monitoring activities, not enforcement. ''After the politicians in their capitals decide on the terms of handling a dispute or a violation, we then conduct the dialogue on the ground. If there is a major violation, it ultimately goes back to the politicians,'' explained a Fijian duty officer.

Noting that both the Palestinians and the Israelis have spent much of the time since July 24 deploying new weapons and troops in the south, one of UNIFIL's executive officers predicted that the only ''progress'' to come out of the Habib mission would be finding means to maintain the status quo, a lull in the fighting. For few here believe the situation in southern Lebanon can be resolved - and UNIFIL withdrawn - until the broader Middle East dispute is settled.