Ground attack is first in Nato history: British SAS troops help US war planes to deliver a timely warning to Serbs that 'safe areas' must be respected, writes Christopher Bellamy in Split

UNITED STATES F-16 aircraft yesterday launched the first offensive ground-attack mission in Nato's 45-year history. The regional alliance, acting on behalf of the UN against the Bosnian Serbs who were attacking the UN 'safe area' around the town of Gorazde in eastern Bosnia, reportedly hit two Bosnian Serb tanks in what was intended to be a precise attack.

An elite squad of British SAS troops in Gorazde tonight directed US war planes to bomb Serb forces threatening the besieged Muslim enclave.

The seven-strong, highly specialised unit gave precise locations of Serb forces surrounding the enclave. Several patrol groups from the Hereford-based SAS regiment were ordered into a number of Muslim enclaves following a request from Lieutenant-General Sir Michael Rose, the UN commander in Bosnia and a former SAS officer and commander.

Trained to operate in small self- sufficient patrol teams they are the ideal reconnaissance troops to feed back information on frontline positions and weapons.

UN military sources in Zagreb said of the SAS soldiers: 'They were providing information on the ground which would have a bearing on air support.'

Local sources said the Serb attack subsided after the strike but and it is possible the UN had left it too late, waiting until the Bosnian Serbs were embroiled in the suburbs of Gorazde, where it is more difficult to launch air attacks without the risk to civilians and property. However, the military effect of the attack was less important than its role as a sharp warning to the Bosnian Serbs that attacks on UN 'safe areas' would not be tolerated.

Over the last few weeks, the UN's special envoy, Yasushi Akashi and General Rose have been trying to get the Muslims and Serbs to make peace.

Last night Nato would only confirm that a 'close air support' mission had been provided 'at the request of Unprofor' (the UN Protection Force in former Yugoslavia).

But the phrase 'close air support' suggests the planes were acting in response to attacks on UN personnel - something the UN command has always sharply distinguished from 'air strikes' on behalf of wider UN aims. UN military observers in Gorazde had come under fire yesterday and it was a short step from General Rose warning at lunchtime that air strikes were a possibility to the Nato action late in the afternoon. Given the time required to authorise the first action of this kind, General Rose must already have made the decision.

Static targets can be found using air and satellite photography but to attack small and mobile targets such as tanks with any chance of success would probably require observers on the ground. There are dozens of tactical air control parties (Tacps) with UN troops in Bosnia, from Britain, Denmark and Canada. But the UN's presence in Gorazde has been minimal, with only a few military observers. Precise attacks on mobile ground forces require the targets to be marked by laser, or in relation to a radar beacon or even with powerful searchlights.

The Tacps favour lasers. When aircraft are sent to attack a target, the lead pilot calls up the Tacp's frequency using a special codeword, and the Tacp directs the aircraft in. The ground observer is responsible for choosing the type of weapon. The favourite aircraft against tanks is the US A-10, which makes yesterday's attack unusual.

(Photograph omitted)