A Royal Marine who made bombs for dissident republicans faked his support for their cause as he was "frozen" with fear, a court has been told.
Ciarán Maxwell was said to be trapped in an "intolerable double life" where he was a "Royal Marine by day and republican bomb maker on leave".
He admitted a series of terror charges ahead of the pre-sentence hearing.
An Old Bailey judge said he must now decide if Maxwell is dangerous, and if this is a case for life imprisonment.
The 31-year-old grew up as a Catholic in Larne in County Antrim and later moved to England, having enlisted in the Royal Marines in 2010.
After his arrest last year, police found 43 hides where he had stashed weapons including anti-personnel mines, mortars, ammunition and bomb-making materials.
The items found buried underground included a Police Service of Northern Ireland (PSNI) uniform and and adapted PSNI pass card.
However, pleading for mitigation, a defence barrister told the Old Bailey that Maxwell would not have used violence to support a cause.
'Frozen and scared'
He said his client had no long-lasting republican ideology and was not ideologically driven.
The pre-sentence hearing has already been told how Maxwell began acquiring weapons after meeting up for drinks with an old schoolfriend from Larne and saying too much about his military background.
Niall Lehd was an alleged member of the Continuity IRA (CIRA) and was later jailed for possessing explosives.
The barrister claimed: "(Maxwell) was in effect forced, to use his own words, to pretend to have republican sympathies he did not in fact have.
"Fear of being in way above his head was effectively what paralysed him from stopping the conduct which brings him before this court."
Quoting Maxwell's own words, the defence barrister added: "I didn't know who to turn to and what to do.
"I felt frozen and scared to make a move which would potentially reveal the life I had been leading."
'Sending a message'
Maxwell made 14 pipe bombs for dissidents, four of which were used in Northern Ireland.
On Friday. the court heard two of the pipe bombs were used after Maxwell's arrest on 24 August 24 last year.
His defence barrister suggested they may well have had an element of "sending him a message" to do what was expected of him.
He said Maxwell's "criminal terrorist associates" would now wish him and his family "serious ill".
However, the prosecution claimed Maxwell's offences had threatened democratic government and the state.
The former Marine was not in court, but appeared by video link from Woodhill Prison in Milton Keynes.
Considering the evidence on the third day of the hearing, the judge said the most important parts of any terrorist organisation are the "command structure and engineering department".
He described Maxwell's actions as a "prolific production by part of the engineering department, if not the engineering department".
The judge is expected to pass sentence on Monday.