The risks in securing a relief road to Sarajevo

WESTERN nations sent signals of possible military action to Serbia yesterday as two US warships headed into the Adriatic and the French dispatched helicopters to Sarajevo. But they faced the stark alternative of a high-risk strategy to secure a land corridor from the port of Split to Sarajevo - or action which is largely symbolic.

In practical terms, warship movements are of little use in putting pressure on land-locked Serbia, which gets most of its supplies by land. But they are a political signal that will be seen on Serbian television, if not from Serbian military positions.

Putting pressure on Serbia is one prong of the United Nations strategy; the other is breaking the continuing blockade of the Bosnian capital, Sarajevo.

The only suitable port as a springboard for a relief effort along a land corridor is Split. Dubrovnik is hazardous; even if it were secure, it is not big enough to accommodate a large sea lift.

There are two routes from Split to Sarajevo. One, to the north, via Sinj, Vakuf and Zenica, is more difficult, narrow and circuitous, but runs through areas that are relatively 'Serb-free' and therefore of less interest to Serb forces.

The other runs along the coast and inland, via Mostar, recently captured by Croatian forces. It is a wider road, more suitable for the big trucks needed to carry a large volume of supplies. A railway - the most efficient artery of strategic mobility - runs parallel to it. Although the Croatian militia control most of this route, there is no guarantee that they always will. According to John Zametica, an expert on the military situation in the former Yugoslavia, it is of more interest to the Serbs. It also crosses a number of rivers, such as the Neretva, north of Mostar - over bridges which could be destroyed.

Moving supplies by land is a high-risk strategy, dependent on continued non-Serb control of the routes. To be sure the routes will remain open would require several divisions of troops to secure a corridor 100 miles long and maybe 50 miles wide - to keep artillery and guerrilla patrols well away from the central roads.

It is not an option that appeals to the British or Americans. 'Terribly dangerous,' said a Ministry of Defence source yesterday. 'Nobody who has any experience of this is very keen.'

There have been reports of naval movements but yesterday only two US ships - the cruiser Biddle and the amphibious assault ship Iwo Jima - were moving into the Adriatic itself. Most of the Carrier Battle Group of the US 6th Fleet remained 'in the central Mediterranean', while the one British destroyer earmarked for 'contingency support' was 72 hours' sailing time away, in Gibraltar. The US Battle Group's amphibious group with 2,000 Marines on board was off Greece, but the chances of the Americans committing troops on the ground look slim. Serbia itself is land- locked but Montenegro, still part of the rump of former Yugoslavia, has 80 miles of coastline. If Serbia is blockaded on land and in the air to enforce UN demands, it will try to bring supplies in by sea and so naval forces, of little concern to the Serbs at present, could become influential.