He explained why to BBC News Online.

The decision to bomb is a tragedy.

It is a clear failure of politics. Politics is about choice and finally we in Europe were left with no choice whatsoever.

The stark reality was that either we pack up and leave the people of Kosovo to their fate - which would be ghastly - or we stand firm and carry out something we have threatened, but failed, to do, three times over the last 16 months.

If we had not done it this time the delicate credibility that was left would have been in tatters.

So the decision to bomb had to be taken. It is extremely sad, but inevitable given the circumstances.

It seems to me, as a former military officer, that it is also a decision that would not have been made without the full realisation that bombing will inevitably require a presence of Nato troops on the ground in Kosovo.

The governments involved with the taking of military action have all pledged that the military forces gathering on the border of Kosovo are all there to police or monitor a ceasefire once Serbia agrees to it.

But in my view Serbia might not agree to it.

In which case you have another decision to take.

Do you force a passage into Kosovo or not. It is clear to me that military planners both in Nato headquarters and in individual ministries of defence will have considered the worst case option.

Serious tragedy

That worse case option is that ground troops will have to go into Kosovo against an armed and determined opposition.

If that happens, which would be a serious tragedy and extremely dangerous, then you can rest assured that it would be done effectively by the most professional partnership in the world.

It is supposition for anyone to suggest that there may come a point, if British lives are lost, where the politicians decide that the price being paid is too high and that they order a withdrawal.