IF American soldiers enter Bosnia soon after a peace agreement is negotiated, they may face difficult scenarios:
*A US Army squad leader on patrol sees a group of drunken Bosnian Serb soldiers beating and robbing an elderly Muslim man. But the American is under strict orders to do nothing outside a demilitarized zone.
*A sniper kills a US soldier near a Serb-held town. Frustrated commanders are eager to retaliate, but cannot locate the source of fire and fear killing civilians. The family of the slain soldier asks on US television why Americans are dying to implement someone else's peace.
The Clinton administration insists such situations will not happen under a US-led "peace enforcement" mission. But some UN officials say the scenarios, which did happen to UN soldiers, will confront US troops and leaders.
Other UN officials, however, say Bosnia is ready for peace, and US clout will bring peace to a country whose dangers, they say, are often exaggerated.
The new peace effort's combination of 60,000 heavily armed NATO ground forces and at least $6 billion in international aid money that can be doled out to sides that cooperate will be a devastating carrot and stick that will minimize the risk to US troops.
And events over the last six months - such as NATO airstrikes and the Bosnian government's retaking of a vast swath of territory - have disproved cynics who said nothing could change in the bitter conflict.
"The greatest force in this part of the world seems to be the unexpected. If anyone told you a year ago that the Serbs would be reeling and that NATO bombing would be used, no one would have believed you," says a senior UN official. "If anything, it might work because people are condemning it to failure."
The danger for US troops in Bosnia, just as for UN peacekeepers before them, will be in the details. Enforcing a peace agreement in Bosnia will confront military commanders and individual peacekeepers with unpredictable scenarios, which could drag US peacekeepers deeper into the conflict.
The past could return
Problems could quickly arise if one side fails to carry out political promises it has made in a peace agreement.
Mirroring what has occurred with other failed agreements in the former Yugoslavia, ethnic cleansing could continue on all sides, prisoner exchanges could be delayed, and laws passed by a proposed central government may not be enforced by rebel Serbs.
US Defense Secretary William Perry is emphasizing that US troops will only be involved in policing a demilitarized zone between the warring parties. Halting ethnic cleansing or enforcing national or international law will be left to UN officials armed only with goodwill.
"That's what we're doing right now," warns a UN official. "And it's not working."
UN civilians, officials, or aid workers could be harassed, or blocked from gaining access to certain areas. But under Mr. Perry's proposal, nearby NATO troops will not lift a finger.
"I think that's where the problem is going to be," says a UN official, "separating the two missions."
Some of Bosnia's dangers can be combatted by NATO's high-tech weapons and brute power, but others cannot, according to UN military officials. One hundred and ninety-eight peacekeepers have died during the 3-1/2-year-old UN mission in the former Yugoslavia. With 122 of the deaths occurring in traffic accidents and other mishaps, more US soldiers may be felled by Bosnia's treacherous roads and thousands of land mines than by its bullets.
"I think you're going to see fewer instances of NATO being targeted than happened with the UN," says a civilian UN official. "Most of your injuries are going to be due to mines and road accidents."
But a NATO force will have far more political weapons at its disposal to get the sides to implement an agreement.
The European Union expects to raise at least $6 billion in funds for the reconstruction of Bosnia, and any side that fails to implement the peace agreement could be financially black-listed.
"We've got a lot bigger club to beat all the sides with," says a UN official. "If the Serbs don't want to play the game, they can be economically marginalized just like Vietnam was for 20 years."
The relative success of a US-brokered agreement that ended fighting between Bosnia's Muslims and Croats last year is a model for how a peace agreement can be implemented, according to the UN official. But the Muslim-Croat pact has only worked in some parts of the country.
"In selected circumstances it has worked where the goodwill exists between the parties," says a senior UN official closely involved in implementing the agreement. "I think you're going to see a wide discrepancy in how much of the peace plan is implemented in different parts of Bosnia."
Some parts of the latest US-brokered peace agreement are already considered unworkable.
Bosnian government proposals that are calling for indicted Bosnian Serb war criminals to be turned over to the War Crimes Tribunal in The Hague are difficult to enforce.
US officials say they want to see Bosnian Serbs brought to justice, but aren't willing to have US troops involved in enforcing international law in Bosnian Serb-held territory.
Before NATO troops arrive, every detail of the new NATO operation, including how political disputes will be resolved, must be thought through, UN officials warn. The rules of engagement, which instruct soldiers how they should respond to a certain situation, must be detailed and logical. All US soldiers must know the rules well, UN officials say, something that did not happen among UN peacekeepers.
Complex for US soldier
UN officials fear that Clinton administration and NATO officials - eager to succeed in Bosnia - are not fully thinking through what happens if Serb extremists bar Muslims from entering their territory, Muslim and Croat nationalists start feuding over who gets control of villages they have taken from the Serbs, or a young American soldier sees something he knows he should stop.
"The most extraordinary complexities of the conflict are going to be engaged in by an 18- or 19-year-old boy from Iowa," warns an American UN military official. "That soldier has got to know what he's supposed to do if the Serbs start popping some Muslims in front of him. What is he to do? What is he going to be held accountable for? Where is the American code of conduct in Bosnia?"