"The world must force Croatia to abandon its decision to end the mandate of the peace-keeping troops. Those international power- brokers who decide to support Croatia in this decision will be supporting the war option," said Milan Martic, the President of the self-styled Republic of Serb Krajina, a breakaway territory that covers almost 30 per cent of Croatia.
Croatia's President, Franjo Tudjman, last month ordered UN forces to start leaving Croatia after their peace-keeping mandate expires on 31 March. He argued that the UN operation had helped the Krajina Serb rebels to consolidate control of their territory and, if allowed to continue, would lead to the permanent dismemberment of the Croatian state.
For their part, the Krajina Serbs contend that the UN forces should stay in place until a political solution has been reached to the Serb-Croat conflict. As a result, the Croatian government and the Serbian rebels are locked in a contest of nerves and willpower that could easily end in the second Serb-Croat war in four years.
Mr Tudjman has threatened before to order out the UN, backing down at the last minute. This time, he seems more serious. The UN thinks so, for withdrawal plans are well advanced. Its forces patrol 1,000 miles of ceasefire lines separating Croatian-controlled territory from the Krajina enclave. As from 1 April, the UN will have no authority to prevent incursions by either side or to mediate in local skirmishes.
"The worst-case scenario would be either the Krajina Serbs or Croats or both going for the same piece of ground or UN kit at the same time, with us caught in the crossfire," a senior UN officer told reporters. Others express fears that peace-keepers could be taken hostage.
Mr Tudjman has proposed that the UN forces be replaced by international units deployed along Croatia's pre-war frontiers with Serbia and Bosnia. However, there is no chance that this will happen, since three groups of Serbs - Serbia, the Bosnian Serbs and the Krajina Serbs - would regard it as an attempt to isolate them from one another.
In anticipation of the UN pullout, the Krajina Serb leadership has suspended steps to restore communications and economic ties with Croatia and, most ominously, has formed a joint war council with the Bosnian Serbs. The key figure is General Ratko Mladic, the Bosnian Serb military commander who, for all practical purposes, is now overall commander of Serb forces in Bosnia and Croatia. He operates with considerable independence from Serbia's President, Slobodan Milosevic, on whom the West has pinned its hopes for ending the conflicts in former Yugoslavia.
Neither the Croatian government nor the Krajina Serbs has come close to meeting the other's basic conditions for a political settlement. Croatia's authorities insist the Krajina Serbs must submit to rule from Zagreb, albeit with substantial autonomy, while the Serbian rebels insist on total separation from Croatia, either in the form of independence or union with an enlarged Serbian state.
There is every sign that Croatian public opinion supports the Zagreb government's stance and that Serbian public opinion in Krajina supports its leadership. For both, a reluctance to go to war again is matched by a determination not to make the concessions to prevent it.
People in Zagreb are already making plans to move relatives from the capital, which is within range of Serbian missiles.
UN officers do not expect immediate offensives after 31 March, but warn of a gradual increase in clashes that could develop into war by the summer. Croatia's army has been practising tank assaults on Hvar, an island off the Adriatic coast. Krajina Serbs have been digging trenches in the south and west areas of Croatia near the Bosnian frontier.
In the Serb-controlled region of eastern Croatia, bordering Serbia, the Croatian army would risk intervention by Mr Milosevic's Serbian-led Yugoslav army if it tried to recapture territory. The region contains oil and rich farmland and is the area of Krajina Mr Milosevic would be most reluctant to see return to Croatian control.
An adviser to Mr Milosevic said this week that the President had proposed Serb-held eastern Croatia remain under UN administration for five more years, after which there would be fresh negotiations on its status. To the Croats, however, this looks like an attempt to ensure the region never returns to Croatian hands.
"Croatia is for the peaceful option," proclaimed a front-page headline this week in the Zagreb newspaper Vjesnik. But Mr Tudjman's gamble that the Krajina Serbs will negotiate rather than fight again seems a misjudgement of the Serbian mood. The fears, prejudices and sense of injustice on both sides are so strong that few would bet against another Balkan war this year.
Tomorrow, the Bosnian war