Video report by ITV News Correspondent Geraint Vincent
A former Royal Marine who supplied bombs to dissident Irish republicans has been jailed for 18 years.
Ciaran Maxwell, 31, stashed anti-personnel mines, mortars, ammunition and 14 pipe bombs in purpose-built hides at eight locations across Northern Ireland and England.
Bomb-making materials were found in barrels and buckets buried in the ground as well as an adapted Northern Ireland police pass card, police uniform and a stab-proof vest.
Police Service of Northern Ireland (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, who is originally from Larne in Co Antrim, was handed an 18-year jail term with another five years on licence.
He showed little emotion as the sentence was handed down.
Speaking after the sentence was delivered, Secretary of State for Northern Ireland Rt Hon James Brokenshire MP said: "I pay tribute to the police and other agencies in successfully bringing this case before the courts. This has undoubtedly saved lives.
"A large volume of dangerous material was seized and this significant jail sentence is an indication of the harm that this individual posed."
Maxwell's 'double life' as Royal Marine and terrorist
Maxwell denied he joined the Royal Marines with the intention of infiltrating them from the outset. Instead he insisted his criminal exploits only started when his friendship deepened with an old acquaintance who was in the Continuity IRA.
He claimed things then spiralled out of control and, as his lawyer put it, he got "in above his head".
Maxwell joined up in September 2010 as a signaller and moved on to 40 Commando at Norton Manor Camp in Somerset in 2013, where he not only stole his colleagues' credit card details, but also a large amount of ammunition.
Over five years, Maxwell stockpiled mortars, anti-personnel mines, pipe bombs, ammunition and handguns in hides as well as an image of an adapted PSNI pass card and uniform.
He wrote a "to do" list on which he identified over 300 targets, including police and military buildings as well as named individuals in Northern Ireland and Britain.
His efforts to build bombs began in 2011 and he sourced information and many of the components he needed from the internet.
Terrorist documents and bomb-making guides, including the Irish Republican Army "Green Book", were found on Maxwell's media devices, along with potential targets.
Life prior to the military
Maxwell grew up in Larne's small minority Catholic community and claimed he suffered sectarianism throughout his early life.
In 2002, aged 16, he was subject to a brutal beating at the hands of loyalists - a separate incident to the one that resulted in his DNA being added to the database.
While he claimed that left him dealing with post traumatic stress disorder, he denied it pushed him into adopting hard-line republican sympathies.
His support for violent republicanism, he claimed, was fake - motivated by fear of dissidents who knew he was British serviceman.
How he was caught
Maxwell could have evaded justice if he not been caught up in an unrelated assault case.
His suspected involvement in the violent incident led to his DNA being stored on the national database even though he was not prosecuted, and that was how detectives investigating mysterious arms dumps in Northern Ireland linked them to a serving Royal Marine in England.
It was not the only piece of good fortune that led to Maxwell's terror plans being foiled.
Police say the first two of his 43 weapons hides were discovered by accident in forest parks in Co Antrim - one by a dog walker, the other by a camper.
The discoveries at Carnfunnock and Capanagh forest parks last year sparked a major operation involving the Counter Terrorism Command (SO15), the South West Counter Terrorism Unit and PSNI.
In August 2016, Maxwell was arrested at his base and a search of Powderham plantation in Devon revealed more weapons stashes.
The hides, near his home of Exminster, contained more improvised explosive devices, chemicals, tools, electronic storage devices, hand-written notes and a small cannabis factory.
In total, police recovered 14 completed pipe bombs, two anti-personnel mines, two explosively formed projectiles (EFPs), 29 firing systems, 33 bomb initiators, two hands guns and a large amount of ammunition.
They seized components for many more explosive devices as well as over 100kg of explosives in Northern Ireland and a smaller quantity in the south west of England.