NEWS ANALYSIS : Follow-Through the Key to Success, Diplomats Say : Bosnia: Peace possible, experts believe, if West stands by commitment and deals with consequences.

As the United States and its allies arrive at the fateful decision that force is needed to halt the Bosnian blood bath, the West faces an even more daunting question: Will armed intervention succeed?

The opinions of diplomats and expert observers in this cradle of the Balkan crisis are as varied and contradictory as those emanating from Western Europe and Washington.

But sources closest to the ground tend to see some chance for eventual restoration of peace and coexistence if intervention comes with a firm commitment to see the job through.

Selective air strikes on Bosnian Serb military targets and the lifting of an arms embargo that has shackled the Sarajevo government will be effective in ending the war only if Western forces are prepared to deal with the possible short-term consequence of even more intense fighting.

Bombing heavy artillery emplacements or the supply lines from Serbia would probably enrage the most extreme elements of the rebel army, prompting defiant officers to move even more viciously against predominantly Muslim civilian targets like the encircled cities of Sarajevo, Gorazde, Bihac, Zepa and Srebrenica.

That would require continued and wide-ranging air patrols and follow-up strikes on any heavy guns missed in the first raids and used by the Serbs to fire in retaliation.

Sending weapons to the Bosnian government forces after leaving them exposed to Serbian attacks for the past year is likely to foster some revenge-taking, especially in the rural areas where Muslims have suffered the worst aggression.

But some Belgrade-based diplomats say the consequences should not be viewed as deterrents to intervention, rather as evidence of the mounting costs of delay.

“We will no doubt see more killing in the short term” if the arms embargo is lifted, predicted one Belgrade-based diplomat. “That is not an argument for not doing anything but an indication of what happens if you don’t do anything.”

Although some in Washington warn that Serbs could respond to the destruction of their heavy artillery by switching to smaller weapons to finish off targeted Muslim communities, the rebels have shown little taste for combat on a level playing field.

The Bosnian Serbs have succeeded in taking 70% of the republic solely on their artillery advantage, encircling civilian targets and pounding them until the inhabitants flee. There has been little hand-to-hand combat, and where that occurred the Serbs often lost ground.

While nationalist media and brash commanders portray the Bosnian rebels as a fierce fighting machine, they took most of the territory during the first two months of the war when they were under the command of the Yugoslav federal army. Weakened by the federal pullout last May and the influx of unruly irregulars, the rebel army is now unorganized, undisciplined and lacking any reliable chain of command.

Rogue politicians talk of fighting to the last man and dying for the cause of Serbian unity. But some military analysts, like Milos Vasic of the opposition Belgrade weekly magazine Vreme, consider the Bosnian Serbs firing on civilians to be nothing more than “drunken rabble” likely to run for cover in Serbia if ever confronted with serious force.

If the Bosnian Serbs are truly determined to fight to the death, as the more radical leaders contend, Western supply of guns to the Muslims would likely instigate more killing, but with the casualties more evenly spread along ethnic lines. To date, at least 80% of the estimated 150,000 Bosnians killed or missing have been Muslim civilians.

Before any decisive intervention, many of the 9,000 U.N. troops based in Bosnia to assist in the delivery of humanitarian aid would have to be withdrawn to prevent their being taken hostage or used as human shields by the Serbs.

The relief effort on which more than half of the Bosnian population depends for its survival would have to be suspended, as aid workers would also become targets for retaliation.

A French battalion based in the town of Pancevo, just north of Belgrade, protectively relocated to the Croatian capital of Zagreb on Friday.

Western embassies in Belgrade would also probably have to be evacuated before intervention to avoid hostage-taking or violent acts of revenge.

Another risk posed by intervention is that it could inspire an outbreak of fighting in Serbia’s restive Kosovo province, either by the Albanian majority desperate to escape repression by heavily armed Serbian police or by the security forces under the control of Belgrade’s nationalist regime.

Fighting in Kosovo could draw Albanians from Macedonia across the border to help their brothers, opening a frighteningly complex regional power struggle as Bulgaria, Greece, Albania and Turkey pursue historic territorial claims.

Intervening forces would have to be prepared to take action against the Serb-led remains of Yugoslavia if their strikes on Bosnian targets triggered an attack on Kosovo or prompted the still-powerful Yugoslav federal army to move in to defend the Bosnian Serbs.

However, federal army Chief of Staff Gen. Zivota Panic indicated last week that he would keep his troops out of any clash with Western forces as long as strikes were limited to Bosnian Serb targets.

Another casualty of the use of force by Western governments would be the proposed peace plan drafted by U.N. envoy Cyrus R. Vance and Lord Owen of the European Community. Owen said Saturday, as the Bosnian factions were gathering for a new round of talks in Greece, that there was reason to hope the Serbs were reconsidering their rejection of the plan.

But Washington appears to have decided that the plan--often criticized as an attempt to stop the war by appeasing the Serbs--is not worth saving or would require too much force to impose.

Hundreds of thousands of troops would be needed to police the borders of the 10 provinces Vance and Owen have proposed, as well as to oversee what would be massive relocations of minority populations to areas destined for their ethnic group’s control.

Opponents of the Vance-Owen plan argue that if the West is going to commit that many ground troops, it should define its mission as peacemaking, not peacekeeping, and seek to restore an integrated Bosnia rather than solidify the ethnic divisions imposed by the Serbs.

One of the most destructive consequences of intervention in Bosnia might be the message sent to neighboring Croatia, where nationalist forces are eager to recover huge areas of the republic seized by Serbs in 1991.

The use of force to roll back Serbian territorial gains in Bosnia would likely inspire Croatian forces to intensify efforts to recapture their own Serb-occupied lands, resulting in deadly clashes between the rebels no longer so well supplied by Belgrade and the Croatian troops who have acquired considerable weaponry since the war was frozen by a U.N. peacekeeping plan.

Western countries would have to engage in more forceful mediation in the Croatian conflict, threatening to exclude the republic from European political and economic blocs unless it makes peace with its Serbian minority and guarantees their civil rights.

Even if intervention was to succeed in its aims of knocking out Serbian artillery and getting guns to the Muslim forces so they can reimpose government control, many observers warn that foreign intervention will work only if the West is willing to oversee a massive and benevolent occupation force committed to building a democracy on the Balkan ruins.

Observers insist that the region will need its own version of the Marshall Plan, by which the victorious World War II allies deployed troops, civil administrators and vast resources to vanquished Germany to instill hope among the defeated and guard against the birth of another despotic regime.

While there has been no indication from U.N. member states that they are prepared for such protracted and costly involvement, some warn that anything short of a full commitment will bring disaster.