DESPITE the unprecedented battlefield successes of the Muslim-led Bosnian Army and Bosnian Croat forces over the past two weeks, their Bosnian Serb foes have not yet lost their overall mastery of the conflict.
``It's still a bit too early to say whether the balance of power has shifted. There has been no real collapse by the Bosnian Serbs,'' a senior United Nations military officer said.
UN officials reported heavy fighting throughout the weekend, with little prospect that the renewed bloodletting would end any time soon and allow a resumption of international peace efforts.
The UN military commander in Bosnia, British Lt. Gen. Michael Rose, indicated the UN's annoyance with the escalation of fighting, and he indirectly accused the Bosnian government of using the UN peacekeeping mission as a shield for launching its attacks.
``All sovereign powers have a legal right to recover territory captured by force. But they don't have the right to do it on the back of a peacekeeping operation,'' General Rose told the Monitor.
``The peacekeeping mission is here to create conditions whereby there can be a peaceful resolution,'' he said. ``It is not here to allow one side or the other to prosecute a war.''
Fighting in Sarajevo
Fierce mortar and small arms exchanges raged through Saturday evening between the Bosnian Army and Bosnian Serb rebels in Sarajevo's western boundary, UN officials said.
They said that during the fighting, Bosnian Serb troops entered a UN-guarded heavy-weapons collection point, retrieved several guns, and fired them, claiming a Bosnian Army tank was already violating the city's UN-declared heavy-weapons exclusion zone.
The fighting ended after three NATO jets, enforcing the exclusion zone, flew over the city just before midnight, the officials say.
UN officials linked the battle to an overall increase in tensions fueled by Bosnian Army advances over the last two weeks in northwestern and central Bosnia.
These represent the worst setbacks suffered by the Bosnian Serbs since they set out 32 months ago to establish an ethnically pure state in Bosnia-Herzegovina. (State of Bosnian Serbs, page 7.)
The Bosnian Army Fifth Corps' capture of 95 square miles abutting the northwest Muslim enclave of Cazinska Krajina (known as the Bihac pocket) has driven off Bosnian Serb guns that regularly blasted the main town of Bihac.
But the enclave has since been hit by modified antiaircraft rockets. More importantly, it remains surrounded by Bosnian Serb-controlled territories and areas of Croatia held by rebel Serbs, who have blocked passage to UN aid convoys for months.
The fall of Kupres, 90 miles west of Sarajevo, on Thursday to the Bosnian Croat force - the Croatian Defense Council (HVO) - after a joint offensive with the Bosnian Army, opened part of an important road from the Croatian coast into central Bosnia.
But central Bosnia has long been accessible by other routes. In addition, a UN assessment obtained by the Monitor determined that the Bosnian Serbs had ``likely'' given up Kupres because it was not valuable enough to defend.
The most critical front for the Bosnian Serbs, according to UN officials, is just south of Sarajevo, where the Bosnian Army First Corps has reportedly advanced to within two miles of Trnovo, a devastated town that has changed hands many times during the war.
Advance on Trnovo
By taking Trnovo, the Bosnian Army would cut the main supply route linking Bosnian Serb-held northeastern and southeastern areas and be in a position from which to try to push a corridor through to the encircled eastern Muslim enclave of Gorazde.
In the meantime, the Bosnian Serbs still maintain their strangleholds on Sarajevo, the eastern Muslim enclaves, and their grip on the vast bulk of the territories overrun by the ``ethnic cleansing'' conquests in the opening months of the conflict.
UN officials also warned that the Bosnian Army and HVO could themselves become seriously overstretched if they press their offensives too far.
These all may be key reasons, UN officials and Western diplomats say, why the Bosnian Serb rebels have yet to launch the massive counterattacks their leadership has promised.
Bosnian Serb leader Radovan Karadzic has called his parliament into session tomorrow to consider declaring martial law. His military command has ordered a mass troop call-up, closing educational institutions and threatening to confiscate draft-dodgers' properties.
UN military officers question the Bosnian Serbs' claims of recapturing territory lost south of Bihac, saying it appears the Fifth Corps deliberately pulled back to avoid overextending its lines.
UN officials believe that the Bosnian Serbs are still marshalling their overstretched forces and limited supplies for a single massive counterthrust that would clearly reaffirm their overall domination and restore morale.
``There is clearly a possibility of a counteroffensive being launched by the Bosnian Serb army. At what point it is going to fall, we don't know,'' Rose says.
He and other UN officers agreed that the most likely location will be Trnovo because of its strategic importance.