SCRAMBLING: Afghan troops running to take up positions after gunfire was heard during Sunday's military parade. -- PHOTO: AFP

The assassins penetrated a heavy security cordon to attack with machine guns and heavy weapons.

And they almost succeeded. Bullets hit Afghan parliamentarians a few metres away from Mr Karzai and the US and the British ambassadors. Although certainly daring, the strategy used by the killers is hardly new.

For even the best-protected leader sometimes has to run risks, such as appearing in public during national day celebrations. And it is then, for a few brief hours, that he is most vulnerable.

The communist rulers of Eastern Europe were fully aware of this danger - that's why their security services always made sure that the firearms carried at military parades did not contain a single bullet.

And as an extra precaution, the leaders of the Soviet Union invariably took the salute from a long distance, high above their marching troops.

The fact that Mr Karzai narrowly escaped the assassination bid was a source of joy to many governments: Congratulatory messages poured into Kabul for most of this week.

Nevertheless, the episode is a stark reminder of just how fragile Afghanistan remains. When Western troops first entered the country in late 2001, their intention was to form a government of national unity.

This now looks like a pie in the sky: provincial leaders have little leeway in the government, and all decisions are taken by Mr Karzai himself. The Afghan leader is certainly courageous. But he will now remain confined to his Kabul palace, which is protected by US security agents. And he is unlikely to attend future military parades.