The attack that killed Iran's Supreme Leader Ayatollah Ali Khamenei came not in the middle of the night, as might have been expected, but in the middle of the morning.
That was because the US and Israel decided to take advantage of a piece of crucial intelligence that had arrived hours before.
For months, they had been watching for a moment of opportunity when senior Iranian figures might be meeting and they learnt Khamenei was going to be at a compound in central Tehran on Saturday morning.
They also had a fix on the location of other senior military and intelligence figures meeting at the same time.
For months the US and Israel had been tracking the supreme leader's movements. The exact methods they used are secret although US President Donald Trump in a social media post did hint at them.
