WHEN Army tanks and armored cars rumbled through Belgrade on March 9 to quell anticommunist protests, many Yugoslavs thought martial law was imminent. Those concerns intensified last week as the fractious Balkan federation experienced its worst constitutional crisis since World War II, initiated by Serbia's hard-line Communist leader Slobodan Milosevic.
Ignoring intense pressure from Mr. Milosevic, the Army refused to proclaim a state of emergency after five days of unprecedented student protests. He was forced to back away from a political gamble that had temporarily shut down the federal collective presidency and pushed the nation dangerously near civil war.
Opposition leaders say Milosevic engineered the crisis to protect his influence in Yugoslavia and to keep power in Serbia, the nation's largest republic.
Yugoslavia's Army, led primarily by Serbs and communists, has generally sided with Milosevic. The armed forces share his conviction that Yugoslavia must remain united with a strong central government in Belgrade, the federal and Serbian capital. But the prosperous noncommunist republics of Slovenia and Croatia favor a loose confederation of autonomous states, and they have threatened to secede if an agreement is not reached with Belgrade soon.
The military's decision not to intervene in the recent crisis has sparked intense speculation about its relationship with Milosevic and fueled debate about the Army's ability to prevent its units, which are made up of recruits from diverse ethnic regions, from unraveling along ethnic lines if conflicts break out.
"The Army can certainly move into anywhere in Yugoslavia," says a Western diplomat in Belgrade. "But the big question is: Can it hold itself together?"
Some experts doubt the Army could impose emergency measures across a country made up of so many ethnic groups and contend it has shown restraint in recent weeks for this reason. Many are sure debate over military intervention has caused a deep split in the military command.
A nationwide Army crackdown and martial law would provoke resistance, especially in Croatia, which has a large ethnic Serb minority. Fighting there could trigger an anti-Croat backlash in Serbia, and old ethnic hatreds would quickly flare across the country.
Yugoslavia has been sliding into chaos since the death of Communist strongman Josip Broz Tito in 1980. Elections last year heightened tensions and fed long-suppressed nationalist sympathies. If martial law were imposed, soldiers might fight at first, but desertions would become widespread during a lengthy campaign, many analysts predict.
There are other formidable obstacles. To occupy Slovenia, tanks would have to roll a long way to reach Ljubljana, its capital. Troops moving into Slovenia could also expect to meet resistance.
Although the military last week ruled out intervention while talks continued to resolve Yugoslavia's future, it added that the Army would "under no circumstances allow armed interethnic conflicts or civil war."
The military also said it would tolerate no border changes without prior agreements, in a warning to Slovenia and Croatia not to try to break away without coming to terms with the other republics. It has implied that visible progress is expected in the political talks, long mired in ethnic strife.
"The Army has allowed the politicians to debate and come to an agreement on the destiny of the country," says Miroslav Lazanski, a military commentator for the pro-Communist Politika newspaper in Belgrade, "but the very same politicians should take into account the self-respect of the soldiers," referring to the predicament the military has faced since the collapse of the federal Communist Party last year.
Unlike the changes that took place in the military of former Soviet-bloc countries, Yugoslavia's generals have remained loyal to the Communist ideology, and there has been little change in the military.