Beirut — Divided Beirut, torn by almost a decade of wars both domestic and international, has become one city again. The signs of reunification are everywhere.
Sandbagged shacks and checkpoints along the ''green line'' are eerily empty. The gunmen of the Christian or Muslim militias that manned them have traded their uniforms for civilian gear.
The high earthen barricades and piles of shipping containers or wrecked cars that marked the improvised wall between east and west Beirut are being hauled down. And the only visible guns in the Lebanese capital now are those of the Lebanese Army.
In the first concrete step by the nine-week-old government of Prime Minister Rashid Karami, 9,000 Army troops have been deployed throughout the capital in an effort to bring it under total government control.
The feeling of relief as the first Army troops moved into place Wednesday was immediate. Women and children in the Christian eastern sector threw rice and rosewater as soldiers in armored personnel carriers and trucks rumbled down the streets. In the Muslim west, drivers seemed delighted to wait in traffic that snarled the streets.
As the phased security plan was being carried out Wednesday, the delighted Mr. Karami told his Cabinet: ''The march of salvation has begun, and I hope Beirut will only be the starting point for the rest of Lebanon.''
Yet to many Beirutis, it seemed like deja vu - a repeat of the fall of 1982 when the Army reestablished control of the capital after the Israeli invasion several months earlier and the previous seven years of internal war. The failure of that effort explains the caution felt in Beirut now.
The breakdown of the United States-orchestrated peace scheme in 1982 was attributed to a lack of political reforms that would give the majority Muslim community greater power in a government dominated by the minority Christians.
President Amin Gemayel's lack of progress on reforms after 17 months of US mediation led the Muslims to turn once again to guns to show their determination to bring political changes they felt they deserved.
Beside the regular spate of smaller conflicts, Lebanon has witnessed two particularly violent periods in the past 10 months: last fall's war in the Shouf mountains overlooking Beirut, and February's battle for west Beirut.
Hence, Arab and Western diplomats are cautious in assessing the outlook for the current scheme. True, they say, the scheme which this time is under Syrian rather than US sponsorship may end 10 months of conflict. But it does not guarantee a permanent end to more than nine years of strife that has killed more than 100,000 people.
One Western military analyst described the security plan as ''only cosmetic. The government still has to tackle a nest of political issues that have grown more complicated with time.''
Two massive obstacles still face the government before Lebanon can be reunited as a single nation:
* Constitutional changes that would, at minimum, provide the Muslims and Druzes with at least 50 percent of parliamentary seats and key government posts.
* Finding a formula for ending Israel's two-year occupation of the southern third of Lebanon. In the event of an Israeli pullout, Syria has pledged to withdraw its estimated 25,000 troops from Lebanon's eastern Bekaa Valley and from north Lebanon. The government can now claim to control only the capital and immediate environs.
Lebanese officials admit there is likely to be major opposition from the Christians when it comes to carrying out the reforms outlined at two summits of the nation's warlords held in Switzerland.
The Christian ''Lebanese Forces'' reluctantly went along with the security plan after first rejecting it. But leading members have indicated that they and other second-generation Maronite Christians are prepared to defy their own old-line politicos - who joined the new Cabinet - when it comes to reform that will end the last Christian stronghold in the Middle East.
And in southern Lebanon, the Israeli Army appears prepared to remain indefinitely.
Beirut's English-language Daily Star came forward as pessimistic in an editorial: ''The new security plan is an opportunity to discover what and how much the Lebanese have learned over the past nine years at a cost in blood and destruction so great that its true size will never be known. An opportunity and no more. Make no mistake about that.
''Overnight, the Lebanese will not have learned to love members of other (religious) communities or how to live alongside each other in peace. . . . What follows is bound to be a period of deep suspicion on all sides,'' the independent paper predicted.
A key military source went further: ''Peace will reign for a short time, a month or two. But as the incidents of military violence diminish, then terrorists will rise, the car-bombs and other uncontrollable acts. That has been the pattern in the past and I see no reason to think things will change.
''Any government acceptable to Syria is not acceptable to Israel,'' he explained. ''So surrogates of Israel may take it upon themselves to destroy peace. It was the same before, only vice-versa.''
One significant problem with the security plan is that the Army has not yet reintegrated Christians into the brigade deployed in west Beirut. Nor has it put more Muslims back in the east's brigade; the Army had suffered two waves of Muslim defections since last September. And the Muslim-dominated Sixth Brigade in west Beirut has no access either to tanks or heavy artillery, which remain under the control of Christian-dominated units, sources at the Ministry of Defense admitted Thursday.
Indeed, rather than abolish the political system based on confessionalism, the peace scheme so far has only entrenched it. For example, the Army is no longer controlled strictly by a Christian, but by a military council comprised of all the major religions.
Although in theory this provides equity, diplomats say that it also underlines the degree of distrust and suspicion among the rivals. Envoys are concerned about initial indications that each representative is looking after his own side rather than planning jointly for the good of the nation, even if it means sacrifices by certain factions.
But for the moment, Beirutis are enjoying their peace. Travel agencies have been swamped now that the Beirut port and airport are set to reopen, providing links with the outside world for the first time in five months.
The sprinklers at west Beirut's golf course, close to some of the battle areas, were at work Thursday preparing for players who had left underground shelters to bask in the balmy Mediterranean sun. And the cease-fire committee, usually swamped with work, was so bored that the members sat down together to watch a movie rather appropriately called ''The Battle of the Titans.''