Rapid-Reaction Force in Bosnia Practices for Peace : Balkans: Rescue exercise aims at standardizing procedures among armies before handoff to NATO.

The French Puma and Gazelle helicopters ferrying senior British and French government officials to negotiate a prisoner-of-war exchange are shot down by renegade gunmen.

The chopper pilots are dead, their passengers wounded. A difficult search-and-rescue mission is launched into the treacherous hills of Bosnia-Herzegovina. Fifteen helicopters swoop to the crash sites, pinpointed by American AWACS aircraft, in an effort to extract and evacuate the victims.

So went the scenario acted out Thursday by elite troops who hope to enforce a peace agreement in the next phase of the war that has devastated Bosnia and confounded the West.

On Day One of a U.S.-brokered cease-fire aimed at beginning the end of that war, military planners here at operations headquarters for the United Nations’ combat-ready rapid-reaction force were already practicing for the transition to peace.

Thursday’s exercise was designed to standardize procedures used by different nations’ armies and by NATO and the United Nations to avoid friendly-fire incidents and other mishaps caused by poor communication. It also illustrated the complexity of the future peacekeeping mission, which is to eventually involve a massive influx of North Atlantic Treaty Organization troops, many of them American.

“It is almost confounding to be introducing such a large force into such a small country,” said Maj. Buster Howes, spokesman for the rapid-reaction force, which is taking a lead role in the transition to a NATO-run operation. “The only way to do that is to make sure we have good communications and make sure we are all envisaging the same operation.”

Potential problems range from overly congested communication channels that jeopardize dangerous operations to where to pitch tents and latrines in a country that uses its precious flatland for farming.

Only an overwhelming force can guarantee peace, said Maj. Gen. David Pennefather, echoing NATO and U.S. military officials.

Pennefather is the No. 2 U.N. military commander in Bosnia after Gen. Rupert Smith, head of all U.N. forces in Bosnia. As currently drafted, the NATO plan is to enforce an eventual peace agreement with 50,000 to 60,000 troops, nearly half American, who will be deployed for two six-month periods.

“You can’t trickle in--the whole plan is based on massive deployment,” Pennefather said. “If we haven’t done it in a year, we’ll never do it. That would mean something is stopping it, it means you’ve given up freedom of movement.”

Thursday’s exercise also underscored what many believe will be the fragility of the 60-day cease-fire that began at 12:01 a.m. Thursday.

“We are multinational, United Nations, French, British, Norwegian, American . . . all flying with rules that are not the same,” Brig. Gen. Pierre Lang said in an interview at the headquarters for the Tactical Air Operations and Coordination Center. “And then you have the warring factions who can introduce an element of danger in the flights.”

In the practice scenario, a French Gazelle helicopter is carrying two government ministers--one French, one British--in tandem with a larger Puma carrying a 10-member delegation. They are en route to prisoner-exchange talks when both are shot down by “an uncontrolled faction” firing a surface-to-air missile.

It is up to the Airborne Warning and Control System aircraft to pass to NATO the coordinates of the crash sites. NATO then must relay the information to U.N. commanders here in Kiseljak, about 20 miles northwest of the Bosnian capital of Sarajevo, who dispatch French and British helicopters from their bases in the coastal cities of Split and Ploce.

“Communications is always the problem,” said French Lt. Col. Jean-Paul Palmeros. “Everyone tries to call at the same time.”

About 100 people participated in the operation, which planners here said was the first of its scale and with this level of coordination with NATO. Exercises are scheduled to continue on a regular basis.

“This cease-fire is not new, but it is different,” Lang said. “It has been led by the United States. You’ve given your power. Now everyone is quite sure NATO is committed. There will be very great disappointment if NATO does not come, if American forces do not come. . . .

“That’s what counts in the minds of these guys,” he said, pointing to the surrounding hills, “the role of the United States.”