ZAGREB, Croatia -- In between the fierce squalls that usher in the Balkan summer, builders under contract to United Nations peacekeepers have been pouring cement and hammering arches for twin porticoes of faux Ionic columns outside the two most important doors at mission headquarters. While the stab at recreating antiquity's grandeur may seem pointless against a backdrop of squat military barracks, the colonnades add architectural substance to local fears that the UN Protection Force, or UNPROFOR, has metamorphosed from a temporary peacekeeping mission into a city-state with a life of its own. There is no name yet emblazoned on the frieze of the vaulted arches, but UN workers joke that it should read: Republic of UNPROFOR. With nearly 40,000 troops and employees already deployed in the embattled former Yugoslav republics and another 5,000 on the way, the UN peacekeeping force has expanded during its mere two-year life span to become the largest and most expensive mission in UN history. Its 3,164 civilian employees alone eclipse the work force of Vatican City. Its proposed $1.5 billion budget for the next fiscal year is nearly 50 percent more than that of the UN Secretariat. The mission has its own airline, with two daily flights to Sarajevo and regular services to Belgrade and other peacekeeper venues. There are 11,527 white-painted vehicles plying the roads from this Croatian capital to the tripwire lookouts in northern Macedonia. Thousands of portable living units -- the postmodern version of the Quonset hut -- have created hundreds of remote UN mini-bases. A fleet of buses shuttles translators and secretaries from the crammed headquarters complex to Zagreb hotels and to the airport, creating a transportation system parallel to the city's. While administrators justify the cost and sprawl as investments necessary because of the mission's broad scope, there are growing concerns in the mission area as well as in the West that the UN has built an empire that is more absorbed with keeping itself in business than restoring peace so it can disband and go home. The mission, which has neither the mandate nor the military means to stop the 3-year-old conflict, is increasingly raising questions about the efficacy of peacekeeping in regions where there is no more peace to keep. It is also prodding some Western analysts to wonder whether the ever-expanding and elusive quest for a negotiated resolution will end up costing more in foreign dollars and local lives than a swift and decisive military intervention would have if one had been undertaken at the start. The tab for food aid, humanitarian actions and peacekeeping is generally estimated at well over $2 billion a year. More than 200,000 lives have been lost. "Not a single objective of this mission has been achieved, because it is compelled to remain neutral in the face of an obvious aggression," complained Bosnian Information Minister Ivo Knezevic during a recent interview in Sarajevo. "For UNPROFOR troops, overseeing our people's suffering has become a matter of jobs. "We don't want to sound unfair or ungrateful for their endeavors and the aid that we do receive, but the negative aspects of this mission are now dominating."His chief complaint, that the UN mission is trying to strong-arm the combatants into agreeing to an unjust peace, is, ironically, shared by all warring factions. Serbian rebels in Bosnia-Herzegovina and Croatia accuse the UN troops of trying to reduce their territorial spoils, while Zagreb contends that the world body's presence here has firmed up the Serbs' hold on the one-third of Croatia that insurgents seized in a conflict three years ago. The imperturbable top UN official, Yakushi Akashi, smiles through the accusations of bias, as he does through suggestions his massive mission has become an immovable force. "We are in good shape when we are equally criticized by both parties," the 30-year veteran of UN bureaucracy said during an interview in his penthouse office atop the newly aggrandized headquarters. Akashi waves away questions about how long he expects his mission to persevere, offering vague expressions of hope that it will not be for too long. "Not decades. Not like Cyprus," he said. "I completely identify myself with the parties to the conflict here. I do not want a reproduction of the stalemate we see in Cyprus," where the UN has been involved for three decades. But it is just such a standoff that the Balkan populations and some troop-contributing nations have begun to fear. "I worked at the United Nations for five years, so I'm familiar with its institutional mentality," said Slaven Letica, a political-science professor at Zagreb University. "It is lazy, bureaucratic and institutionally stupid."The people who take part in these missions learn to accommodate the local suffering. They have to develop this indifference as a survival strategy, because they are nice young people who cannot really do anything to help. Their preoccupation becomes that of any other job -- getting by, getting a paycheck, achieving career advancement."In the unlikely event that the mediation efforts wring out a settlement, NATO has promised to help implement it by sending 50,000 troops. That would more than double the mission's already unwieldy size. As one European officer in Sarajevo quipped, "If the UN can keep 40,000 people busy without having produced a single agreement, imagine what the force will grow to if we ever get a real cease-fire."