The possibility of US forces being assigned to the United Nations could bring troop numbers closer to those estimated to be needed to police any division of Bosnia. In recent days, estimates of up to 50,000 have been produced.
These figures are part guesswork. The British battalion group there consists of 1,000 frontline troops, with 1,500 in support. It is certain that to control areas 9 and 10, for which Britain is likely to be made responsible, will take a 'brigade plus' - 5,000 frontline troops. That is the origin of the 50,000 figure for the 10 regions.
However, the map drawn up as part of the Vance-Owen peace plan was never intended to be set in concrete - it is a basis for negotiation. The US believes the map, which is constantly changing, is too favourable to the Serbs.
The plan may depend on the assets available, rather than the the other way round. Whitehall sources suggest a more optimistic 20,000 to 25,000 troops. But where would they come from? And where would they go?
Italy and Germany would have problems sending large contingents to Bosnia because of their recent history. The same probably goes for the Turks - Bosnia was part of the Ottoman Empire. The ethnic and religious balance of UN forces is important. The force in Sarajevo - Egyptians, Ukrainians and French - mirrors, roughly, the religious make-up of the land: Muslim, Orthodox (Serb) and Catholic (Croat).
The British Army is stretched. A brigade of 5,000 extra troops for Bosnia is about the limit. The Canadians, who have 4,700 peace- keepers around the world, are also stretched. They have about 2,500 troops in former Yugoslavia. Military planners yesterday speculated that the US might provide another 15,000 troops. That would leave maybe 5,000 to come from Russia and Ukraine.
Although sectors have not been allocated, observers say the US might provide troops for the areas in the east, up against the Serbian border. Putting the Americans in the Serbian areas capitalises on their high political profile. US troops lack experience in this type of task, which would be more complex than that in Somalia. But they should be able to undertake the three main tasks in an internal security mission: reassuring the local population, deterring violations of the agreement and taking action against anyone who does violates it. The last would probably mean arresting people and handing them over to the local authorities, although the US is proposing full-scale enforcement - seizing arms dumps by force, for example.
Although the map of Bosnia is frequently divided in terms of areas, the war there is about key points. Towns are dominated by different ethnic groups, but a town is no use unless it works. Much of the fighting is over power stations, dams and and other key points in the infrastructure. The other key points are former Yugoslav arms factories. This strategy explains much of the fighting that has taken place.
Theoretically, a single observer could monitor such a key point. If the plan were violated, rapid reinforcement would be needed. A large power station would require at least a company (100 troops) but more likely a battalion (650) to secure it.
Other key points would be political or religious sites, critical points on routes, and where those routes cross peace lines. UN troops would also man vehicle checkpoints and observation posts and carry out 'framework patrolling' as part of the deterrence role - random searches and checks designed to keep the parties on their toes.