Beirut — In Lebanon, the Christian militiaman explained patiently, ''security is by consensus.'' Lebanon's many factions have so far failed to reach consensus on the government plan to deploy troops some 18 miles south down the Mediterranean coastal road.
That has embarrassed the government, which has insisted in negotiations with the Israelis that the Lebanese Army is a viable force that can police the south should the Israelis end their 30-month occupation of that region.
The failure to reach consensus has also threatened Beirut's fragile on-again-off-again peace. Each day this week, Druze and Christian militias have fired on one another.
''Lebanon's credibility is at stake,'' said Salim Hoss, a former prime minister and current labor and education minister, in an interview.
Mr. Hoss, a Sunni Muslim, expressed a common fear among Lebanese officials - that Israel, frustrated by the lack of progress in talks with Lebanon, will unilaterally withdraw from the south at least partially. Israel has said that if no progress has been made in the talks by their adjournment today for a six-week break, it will ''reassess'' its options.
UN sources say the Israelis are discouraged by what they see as Lebanese intransigence, read by Israel also to be Syrian intransigence (Syria is the main power broker in Lebanon). Israel was hoping to reach a ''gentleman's agreement'' with Syria that if Israel withdrew from the south, the Syrians would not allow Palestinian guerrillas to infiltrate through Syrian positions in eastern Lebanon and strike at Israel.
''The Israelis have really made some concessions,'' said a knowledgeable source. ''But the Lebanese just aren't moving.''
The Lebanese have insisted on an unconditional Israeli withdrawal from the bottom third of their nation which Israel has occupied since June 1982. But all factions here now fear the consequences of a sudden withdrawal.
''The deployment of the Army is important in more than one respect,'' Hoss said. ''The Lebanese military will have to be standing ready at the Awali River in case of an Israeli withdrawal from Sidon. If the Israelis partially withdraw, it will be from Sidon to the Zahrani River. The Lebanese government can't speak of a role for us unless it is there.''
Standing in the way of the Army deployment is the powerful militia of Druze Cabinet minister Walid Jumblatt. Mr. Jumblatt's forces have controlled much of the coastal road from Beirut to Damour since February.
The Druze now say that the planned deployment of the Army along the coastal road threatens their stronghold in the Shouf mountains near Beirut. They want to avoid a repeat of the massacres that followed Israel's sudden withdrawal from Beirut in September 1983. The Druze still see the Army as the tool of the Christians.
''How can Jumblatt be seen as allowing the Army back into the Shouf after he has thrown them out before?'' Hoss asked. ''The problem for the leaders of each of Lebanon's factions now is that they cannot give anything because their people have suffered so much. So any concession looks like too much of a concession.''
Jihad Zuheiri, an aide to Jumblatt, said the Druze rejected the Army's first plan because it called for the troops to set up permanent roadblocks along the coastal road, and to extend their hold a mile inland to include part of the Druze-controlled hills, overlooking the road.
Earlier this week, the Druze accepted a plan that would keep the Army on the road, not allow permanent roadblocks, and would require the Christian port of Jiye to be closed. The Christians have been using Jiye to move people and supplies to the south.
But a spokesman for the Lebanese Forces, the consortium of Christian militias , said that the Druze-backed plan was unacceptable.
''The Army has to be on the hills,'' said Massoud Ghowi. ''We cannot allow the Army to go down the road without protection.'' Mr. Ghowi said the plan favored by the Druze ''cannot ensure the safety of our people from Damour (north to Beirut).''
The Lebanese Forces, Ghowi said, are concerned about the pocket of Christians who live in the Kharoub region south of Beirut.
Lebanese from different factions expressed doubts about the ability of UNIFIL , the UN peacekeeping force in south Lebanon, to keep the peace should the Israelis leave.
Israel has said it wants UNIFIL to expand its forces and take over areas Israel evacuates. Lebanon has refused such an expansion.
The Lebanese are ''afraid of UNIFIL's being used to separate a portion of Lebanon from the rest of Lebanon,'' Hoss said. Neither Lebanon nor Syria is in a position to guarantee Israel's security, he said.
''Syria cannot. If it did, it would lose its credibility in the Arab world.''
The stalemate in the talks, most of those interviewed said, is both dangerous and virtually unsolvable.
''It is all connected with the crisis of confidence that governs all our relationships in this country,'' Hoss said. ''The Army doesn't trust all the militias and so (it) wants to go in force wherever it is deployed. The militias also don't trust the Army. So nothing is done.''