Nato takes a step into the unknown

About 3,500 British soldiers and a similar number of French troops are digging in for a fourth Bosnian winter as the Nato Implementation Force (I-For) takes over the military peace-keeping operations from the UN Protection Force. Another 10,000 British, 7,000 French and 20,000 Americans are on their way. While it is a new venture for the Americans, this winter will be different also for the British and French.

From yesterday - D-Day in the timetable drawn up at Dayton - if their freedom of movement is impeded, if local factions contest their authority or violate the ceasefire, Nato troops may open fire with weapons which the locals have not yet seen, including 60-ton US Abrams and British Challenger tanks, and self-propelled guns able to score a first-round hit at 15 miles.

The Nato operation, "Joint Endeavour," and its British component, "Resolute," ought to be much simpler than the complex and chaotic task undertaken by the UN. It will, nevertheless, be without precedent in peace-keeping history. Most "traditional" peace-keeping missions, like those in Cyprus, the Middle East and Cambodia, have been interim arrangements, with peace- keepers holding a line while negotiations continue. In Bosnia, Nato will be implementing an agreed peace.

Preparation for elections,refugees, and humanitarian aid will not be Nato's concern, although the civilians charged with these tasks will probably call on Nato troops for escorts. The work of the other organisations is being co-ordinated by Sweden's former prime minister, Carl Bildt, known as the "Higher Representative" who received his commission from the Security Council but represents the EU and the Organisation for Security and Co- operation in Europe as well.

For Nato, everything should be relatively simple. The only uncertainty should be the interpretation of agreed lines on the ground: the border between the Muslim-Croat and Serb entities in Bosnia and the demilitarised zone stretching for two kilometres on either side.

The implementation of an agreed peace poses a dilemma. If one side interprets the agreement differently, Nato will find itself in the business of "enforcement" - intervention to impose a solution. It is equipped to "enforce" a view, but it may have to think on its feet to formulate it. Within a context of "implementation" there may be islands of "enforcement".

Nato planners have the process of deployment, implementation and transition to peace laid out on a flow chart, but admit the process is "extremely fluid", not least because of the weather. Yesterday authority was transferred from the UN Protection Force (Unprofor) to I-For and joint military commissions comprising the warring factions were set up under Nato chairmanship to oversee mapping of hundreds of miles of demarcation line which follow the ceasefire line reached at the end of hostilities in October, with a few exceptions.

A 700sq-mile area, known as the "egg", around Mrkonjic Grad, overrun by Croat forces, will be returned to the Serbs. The area north of Sarajevo will be ceded to the Muslim-Croat federation, as will a corridor from Muslim territory south of Sarajevo to the former pocket of Gorazde.

The "egg" is pretty well deserted, apart from Croat troops, and although it is the biggest area to be transferred, the British troops who will be responsible do not expect too much of a problem. The Serbs who lived there all fled, and no Croat or Muslim civilians have attempted to settle there.

The situation around Sarajevo, where Serbs lived cheek-by-jowl with Croats and Muslims, is far more sensitive.

In addition to 60,000 Nato troops, 2,000 UN civil police are being deployed, to give confidence to the local civilians. Positions on the ceasefire line around Sarajevo will be transferred or vacated by next Wednesday.

The next and most difficult milestone is "D plus 30" - around 18 January, by which time the former warring factions must release prisoners and vacate the zone of separation between the "entities". All mined areas must be marked. Civilian groups will have to be disarmed and "non-local forces" - the mujahedin, about half of whom are Islamic extremists from outside Bosnia - must withdraw. These are probably Nato's biggest concern. By then, I-For should have secured territory to be transferred.

Nato must ensure that such areas are "cleared" of local troops by D plus 45 , at the beginning of February. Then, on D plus 90, around 18 March, the new owners will be able to occupy the areas that have been transferred.

Finally, by D plus 120, a month later, local forces must have been moved to holding areas. Any forces outside those areas must be demobilised, and the two "entities" - the mini-states within Bosnia - must provide details of the strength and deployment of their forces.