Manchester bomber Salman Abedi was given the go-ahead for his suicide attack by online Islamic extremists.
Hard-liners urged him to “show no mercy” before the blast which killed 22 and injured more than 100 at the Ariana Grande concert.
And a series of sinister messages have revealed he was planning the outrage at least nine months before he blew himself up.
The FBI has obtained details of shadowy internet conversations between Abedi and suspected extremists in Syria and the US.
He had logged on to ask for advice about his rucksack murder plot.