Clearly, the Muslims still have a long way to go. The Bosnian Serbs control up to 70 per cent of Bosnia, retain a distinct advantage in heavy weaponry, and are capable of overrunning the three small Muslim enclaves of eastern Bosnia - Gorazde, Srebrenica and Zepa.
But if any party to the conflict is worrying this weekend about what the future may hold, it is the Bosnian Serbs, not the Muslim-led forces. International outcasts, starved of military and economic support from their former patrons in Serbia, and forced to fight with limited resources on several fronts, the Bosnian Serbs are in their most vulnerable condition since they rebelled against Bosnia's independence in April 1992.
This is the underlying reason for the Bosnian government's new offensive in the Sarajevo area. The operation's short-term objective is to cut the Bosnian Serbs' supply roads around the capital and ease the pressure of the siege, which before long will be threatening to enter its fourth successive winter.
But the Bosnian government appears to have even more ambitious long- term objectives. The Sarajevo operation is being conducted in conjunction with a so far highly successful Croat offensive against Serb forces in western Bosnia.
The intention of the Muslims and Croats, allies once more after fighting an ugly war in central and southern Bosnia in 1993, is to squeeze the Bosnian Serb heartland between central Bosnia and Croatia's border with western Bosnia. A related aim is to block off the vital supply route linking the Bosnian Serbs to the Krajina Serb rebels of Croatia, who control about 25 per cent of Croatia's territory but who are on the defensive after having surrendered the enclave of western Slavonia last month.
The Croats have been advancing since last November on a wide front in western Bosnia and last week announced the capture of Mount Sator, an important peak near Croatia's border with Bosnia. A Bosnian Croat military spokesman, Ignac Kostroman, said: "The Serbs' increasing losses at the front mean they find themselves in a hopeless situation. This has resulted in major reversals of fortune on the battlefield and should influence a political solution for the internationally recognised state of Bosnia- Herzegovina."
Since their initial successes of 1992, when they swept through largely unarmed Muslim communities, the Bosnian Serbs have found the war a hard grind. They have not only failed to induce the Bosnian government's capitulation but have discovered themselves fighting increasingly well-equipped, well- trained and highly motivated Muslim armies. Not for nothing are some Muslim units known as "the avengers". Their members are men who were expelled from their homes in the early months of the war, whose relatives and friends were sometimes killed in cold blood. They need little encouragement to fight anywhere in Bosnia.
By contrast, Bosnian Serb soldiers are reluctant to do battle outside their home areas. For more than two years, many have preferred to sit on hilltops and fire the odd artillery round at their former Muslim neighbours. This immobility is finally costing the Bosnian Serbs dear.
Two months ago the Muslim-led forces pushed them off Mount Vlasic, the mountain in central Bosnia where the most important telecommunications towers left in former Yugoslavia are located. Last month government forces in the Bihac pocket of northwestern Bosnia captured Ripac, an important link between Bosnian Serb and Krajina Serb positions. None of this is to suggest that the Muslims and Croats could have the war wrapped up by the end of summer. But the balance of the war is turning in their favour, and if the Bosnian Serbs want to regain the upper hand they will need at least one of two factors injected into their side of the equation.
The first is a renewal of support from Serbia. President Slobodan Milosevic cut off the Bosnian Serbs last year for refusing to support an international plan to divide Bosnia roughly in half between a Muslim-Croat federation and the Bosnian Serbs. Some arms, fuel and other supplies have trickled through Belgrade's blockade, but evidently not enough to satisfy Radovan Karadzic and his Bosnian Serb friends.
Mr Milosevic is unlikely to throw Serbia's military weight behind Mr Karadzic under any circumstances, but he might support a different Bosnian Serb leadership if it seemed that the Muslims and Croats were steamrollering their way to victory. On the other hand, he may decide that Serbia's need to have United Nations sanctions lifted and return to international respectability is so urgent that it is not worth supporting the Bosnian Serbs at any price.
The other factor is the West's policy. Shameful though it seems to the Bosnian Muslims' and Croats' sympathisers in Western countries, Western governments would rather see an immediate ceasefire than a successful Muslim-Croat operation to end Sarajevo's siege and roll back Bosnian Serb war gains.
One interpretation of the Anglo-French initiative to expand UN operations in Bosnia by creating a "Rapid Reaction Force" is that it is intended to smother any attempt by the Bosnian government to intensify the war. True or not, the fact is that the US, Britain, France and Germany have all urged the Bosnian and Croatian governments in the last four days not to take the war to the Serbs.
It may already be too late. The Bosnian government has clearly had enough of being bullied into submission by polite Western diplomats. But the latest Muslim-led offensive remains a huge gamble.
A wider war in the Balkans is not just an exaggerated Western fear, and if it came to pass it is hard to see how the Bosnian Muslims would benefit.Reuse content