An Algerian man with suspected al-Qaeda links has been found guilty of downloading information on how to blow up a passenger jet.
Police believe Abbas Boutrab is a false identity
Abbas Boutrab, 27, was arrested in Newtownabbey, near north Belfast, over suspected immigration offences.
Police later found computer discs with downloaded bomb-making instructions. Boutrab had denied the terror charges.
Crown Court judge Mr Justice Weatherup said the information could have been of use to terrorists.
He also said that modifications made to the circuitry on a cassette player indicated intent.
"I am satisfied that his possession of the material was not out of curiosity but was for terrorist purposes," the judge said.
Boutrab has spent the last two-and-a-half years on remand in Maghaberry Prison.
During the trial the court heard computer discs containing instructions on how to make explosives for use on board aeroplanes, and how to carry out an attack, were found at his flat in the Whitehouse area of Whiteabbey.
Details on how to make a silencer for an assault rifle were also found as were a number of false identities and passports.
Boutrab was tried under the Diplock system, where a judge in a terrorist case sits without a jury and will be sentenced next month.
Speaking after the trial Detective Superintendent Esmond Adair, who led the investigation, said "a very dangerous man" had been taken off the streets and that Abbas Boutrab was not his real name, but another assumed identity.
"Abbas Boutrab remains a determined terrorist who has become expert in the procurement and forging of false identities," he said.
"I believe he has a strong allegiance to a terrorist group that is linked to the al-Qaeda network."
He said police believed Boutrab had lived and operated throughout Europe and that the discovery of an international terrorist in Northern Ireland was "unusual."
"It is worthwhile remembering that those who are involved in this kind of terrorism are extremists and in no way representative of the vast majority of the law-abiding Muslim community," he said.
He added that Italian, Dutch, French and Irish police forces had assisted the investigation along with the FBI and the security service.