Wesley Clark, Nato's Supreme Allied Commander for Europe, gave a graphic account of the incident revealing that, having hit the train unintentionally once, the pilot targeted a second bomb on the other end of the bridge, only to wreak more damage on the train.
The description of the event, which Nato acknowledged was its most unfortunate episode so far of "collateral damage", illustrates how split-second judgements and luck decide life and death in modern warfare.
Showing cockpit film of the incident, General Clark described the incident at a packed press conference at Nato's headquarters in Brussels. For once, the pilot's-eye-view video, now a familiar feature of televised war coverage, was used to illustrate the snap judgements that air crews have to take, rather than their mechanical success in destroying military targets.
General Clark described how, as the pilot "stared intently at the aim point, all of a sudden - with less than a second to go - he caught a flash of movement".
That proved to be the train, identifiable on the film, moving very swiftly from left to right of the pilot's vision. General Clark said the pilot "couldn't dump the bomb", partly because it was a "remotely directed attack" at that point outside his command.
More surprisingly, although the pilot realised what had happened, he decided to attack the other end of the bridge, although much of the area was, by now, concealed by smoke. "At the last minute again," continued the general, "in an uncanny accident, the train had shunted forward from the initial impact."
Because of its movement towards the other end of the bridge, the second strike caused more damage. When journalists arrived at the scene three hours after the attack, three railway carriages had been incinerated and were still hot and smoking.
With a typically military degree of understatement, General Clark added: "It was certainly an unfortunate incident which we and he and the crew and all of us regret." He added: "It was one of the regrettable things that happen in a campaign like this. We are all very sorry for it."
Mindful, perhaps, of the propaganda aid that the bridge attack has given to the Yugoslav President, Slobodan Milosevic, yesterday's demonstration at Nato seemed designed to show that the alliance was not holding back any information about the attack. However, it still left unanswered the question of why the bridge was attacked for a second time once the train's presence was known about.
Later, a senior air commander said that the pilot would have been under orders to attack the bridge twice, and said other distractions in the cockpit might have drawn the pilot's eye from his screen.
The incident has caused particular concern at Nato because, throughout its three-week air campaign, military chiefs have stressed the lengths to which they have gone to shield civilians from their war with Mr Milosevic. That determination was repeated yesterday, General Clark promising that Nato was "going to do everything we can to continue to work the air campaign in an effective and systematic manner that avoids needless casualties and avoids collateral damage".
As for the identity of the pilot whose judgement will continue to be debated, Nato declined to reveal either his nationality or the type of the aircraft involved. But General Clark defended his decision to return for a second attack on the bridge. "He was trying to do his job and take the bridge down," he said.Reuse content