A terrorist who infiltrated the British military has been jailed for 18 years for supplying bombs to dissident Irish republicans.
Ciaran Maxwell stashed anti-personnel mines, mortars, ammunition and 14 pipe bombs - four of which were later used - in 43 purpose-built hides at eight locations in Northern Ireland and England.
Bomb-making materials were found in barrels and buckets buried in the ground as well as an adapted Police Service of Northern Ireland (PSNI) pass card, a PSNI uniform and a police stab-proof vest.
The 31-year-old, who is originally from Larne in Co Antrim and was with 40 Commando based at Norton Manor Camp in Taunton, Somerset, at the time of the offences, pleaded guilty to preparation of terrorist acts between January 2011 and August last year, possessing images of bank cards for fraud and possessing cannabis with intent to supply.
PSNI Detective Chief Inspector Gillian Kearney said Maxwell used his military know-how to accumulate and construct his devices, and described the infiltration of the military by a republican terrorist as "very unusual" and "certainly the first case of its kind in recent years".
Sentencing, Mr Justice Sweeney said: "I'm sure that you were and will remain motivated by dissident republican sympathies and a hostility to the UK."
Maxwell was handed an 18-year jail term with another five years on licence.
He was given consecutive sentences of 18 months and two years respectively for possessing cannabis with intent to supply and possessing images of bank cards for fraud.
Maxwell, described by the judge as an "inveterate record-keeper", showed little emotion as the sentence was handed down.
He had appeared in court via video link from Woodhill Prison in Milton Keynes.
The Old Bailey heard that the father-of-one researched targets and discussed plans to attack police stations and officers.
His plot, however, was foiled when members of the public stumbled across his weapons hides by chance.
DNA evidence found on parts of the haul led them to Maxwell, who was on the national database due to his alleged involvement in an unrelated assault case.
Paul Hynes QC, defending, told the court his client was not ideologically driven and would not have used violence for a cause.
He said it was Niall Lehd, said to be a member of the Continuity IRA (CIRA), who was the "instigator" of a joint venture with Maxwell, who had "no long-lasting republican ideology".
Maxwell denied joining the Royal Marines in 2010 with the intention of infiltrating them.
He claimed he faked his support for the dissidents' cause because he was "frozen" with fear and believed old connections wished "serious ill" on him and his extended family in Northern Ireland and England.
The court also heard that he had been brought up as a Catholic in the largely loyalist town of Larne and suffered a fractured skull as a 16-year-old when he was the victim of a sectarian attack.
Maxwell, of Exminster in Devon, was a serving Royal Marine with 40 Commando based at Norton Manor Camp in Taunton at the time of the offences and was deployed in the United States, Cyprus and the UK - but not Northern Ireland - after enlisting in 2010.
He was about to be promoted to corporal before he was discovered and discharged from the Marines.
The judge admitted there was "insufficient evidence to be sure that you (Maxwell) had any sinister motivations at that stage", but that the marine had grown to become "meticulous in the planning and execution" of his work.
Mr Justice Sweeney said: "There was sophisticated offending on a substantial scale which took place over a period of more than five years.
"There was clearly the potential for the deployment of many bombs of varying types and sizes against multiple targets, with the ultimate intent of those planting the devices being to kill.
"There was considerable planning, including attack planning, research, and the acquiring of large amounts of materials including police items for use in disguise.
"You were strongly committed to the cause.
"To state the obvious, a skilled bomb maker is of considerable importance to a terrorist organisation like the Continuity IRA."
The judge said some of the ammonium nitrate recovered in Northern Ireland could have been used to make an explosive larger than "the notorious Enniskillen bomb", the Poppy Day bombing in 1987 which killed 11 people and injured 63 others.
Sue Hemming, head of the special crime and counter-terrorism division at the CPS, said: "The large amount of chemicals, explosives and components Maxwell stockpiled could have caused serious harm and Maxwell accepted by his plea that he intended to assist others to commit terrorist acts.
"During police interviews, Maxwell never fully explained the motives behind his actions, but the public is undoubtedly safer with these items out of circulation. Sue Hemming, head of the special crime and counter-terrorism division at the CPS
Commenting after the sentencing Assistant Chief Constable Stephen Martin, Head of the PSNI’s Crime Operations Department, said that the combined work of the public, who played a part in alerting authorities to the hides, along with the police had, "disrupted the activity of a dangerous individual and removed a very significant threat".
He said: "The hides uncovered at Larne and surrounding areas collectively, amount to one of the most significant seizures of munitions in recent years in Northern Ireland, not to mention the further items recovered in hides in Great Britain.
“It is obvious that these materials and munitions were sourced, gathered and constructed over significant periods of time which demonstrates Ciaran Maxwell’s determination and committed planning. These items are designed to cause damage, serious injury and to kill.
“Ciaran largely worked independently but we know he had a link to a Violent Dissident Republican grouping. It is abundantly clear from the sheer volume of weapons and component parts found that he knew they would be used and would cause serious harm.
“As a result of these finds and the arrest and sentencing of Ciaran Maxwell, there is no doubt in my mind that Northern Ireland and England are safer places to live. It is worth emphasising that a number of these lethal devices were in a state ready to be deployed."
Assistant Chief Constable Martin thanked the public who first alerted police and said this demonstrated the "vital role" the public have in supporting the PSNI.
He added: “Working together, we have disrupted the activity of a dangerous individual and removed a very significant threat.
“While the threat level in Northern Ireland from Dissident Republican violence remains severe, meaning an attack is highly likely; there is limited community support and traction for terrorists. The vast majority of people want to move on from the past, enjoy living without fear and embrace the vibrant place Northern Ireland has become.”
London's Met Police have also welcomed the verdict, with the head of the Met's Counter Terrorism Command Commander Dean Haydon saying that it was "all thanks to members of the public, who noticed suspicious items and reported it to the police".
"This case shows the strength of how police forces work together through the UK's Counter Terrorism Network. As soon as Maxwell was identified as the suspect, we coordinated a large-scale investigation and police operation across the southwest of England and Northern Ireland, which was both extremely fast-paced and complex," he said.
"This has prevented a huge amount of lethal weapons from falling into terrorist hands and an extremely dangerous man is now behind bars."