MI5 chiefs are convinced Scotland's first home-grown al-Qaeda terrorist "would have ended up in a million bits" if they had not managed to stop him.
Despite claims from Mohammed Atif Siddique's family last week that he has been the victim of a miscarriage of justice, investigators paint a different picture.
They believe the 21-year-old, found guilty last week of terror-related offences, was being groomed and brainwashed to carry out a bombing atrocity somewhere in the world.
His email conversations with a suspected al-Qaeda operative, who for legal reasons can only be identified as "the Englishman", indicate what a danger he was, according to security experts.
One told Scotland on Sunday: "If we had lost track of him then we would never have picked up his trail and the next time we did, he would have been in a million bits.
"It could have been on a British shopping mall floor or outside the US embassy in Islamabad or even on a desert plain in Afghanistan targeting UK troops, we will just never know."
He added: "But the fact he was in contact with the individuals he was, places Siddique in a different league to other terror suspects."
The comments were supported last night by a leading al-Qaeda expert, who testified for the Crown at Siddique's trial.
Evan Kohlmann, a Washington-based analyst of Islamic fundamentalism said: "At first glance, Mohammed Siddique might seem to be a reasonably poor candidate as an international terrorist.
Unfortunately, as other recent troubling events in Glasgow and London have unequivocally demonstrated, we no longer live in an era dominated by the monolithic threat of intricately-planned 'organised terrorism.'"