By Stephen Mulvey
BBC News Online Russian affairs analyst
There have been many attempts to kill Akhmad Kadyrov. Few people who know Chechnya would have predicted that he would survive so long.
Kadyrov's allegiance with Putin made him a target for the rebels
Bombers have come close in the past - this time they got a direct hit.
The attack was probably carried out by Chechen rebels, who view him as a traitor.
He was on their side in the first Chechen war of 1994-96, as a religious leader with his own armed detachment.
But later he switched sides, eventually becoming the Russian government's puppet president in what was widely seen as a rigged election.
Any member of the Russian-backed administration in Chechnya is a target for Chechen rebels, but Kadyrov was a target two or three times over.
One more recent grievance was the ruthless behaviour of a militia serving as his personal guard, which has been linked by some analysts to the regular "disappearance" of young men.
Reportedly, the men were given a chance to join Kadyrov's militia, and if they refused they disappeared.
If this is true - that rebel sympathisers were forced to serve Mr Kadyrov - it perhaps explains why people close to him might overlook a bomb placed under his viewing platform at a victory parade.
In a country with a tradition of blood revenge, the disappearances would also widen the group of people wanting Mr Kadyrov's head.
No natural replacement
For the Russian government, Mr Kadyrov is an immense loss. He is a strong-willed man of some standing inside Chechnya, who is on their side.
There are not many of them.
What is more none have been groomed as possible replacements - indeed, other strong candidates were prevented from running in the presidential election.
The huge reliance on Mr Kadyrov is perhaps the main weakness of Russia's plan to stabilise Chechnya.
Moscow rules out talking to the rebels, so it needs credible Chechen leaders from other parts of the community.
And now it has none.
Fears for future
Mr Kadyrov was not much loved by ordinary Chechens and will probably not be greatly missed.
However, there will be many who fear the Russian revenge - the prospect of security sweeps in which young Chechen men are routinely abused, or destructive attacks on mountain villages that rebels have been known to visit.
More generally, the assassination gives rise to uncertainty about the future.
Despite the continued presence of large numbers of Russian troops, and the occasionally deadly attacks orchestrated by the rebels, a degree of stability has returned to Chechnya in the last two years.
Large numbers of refugees have returned, some reconstruction has taken place, some people have found jobs, children have returned to school.
Everyone knows how important these changes are, and how easy it would be to slide back into anarchy.