A Royal Marine who built explosives for a dissident republican group had parts delivered to his late grandmother's home, a court heard.
Ciaran Maxwell, 31, stashed anti-personnel mines, mortars, ammunition and 14 pipe bombs - four of which were deployed - in purpose-built hides in Northern Ireland and England.
The Old Bailey in London heard that there were 43 hiding places at eight different locations.
On the second day of his sentencing hearing, prosecutor Richard Whittam QC said that Maxwell, of Exminster in Devon, had ordered chemicals and other parts over the internet for delivery to Northern Ireland.
The court heard that Maxwell had also carried ammunition with him between England and Northern Ireland by ferry, according to Mr Whittam.
Chemicals and materials to make more bombs, as well as an adapted Police Service of Northern Ireland pass card, a PSNI uniform and a police stab-proof vest, were found by police in barrels and buckets buried in the ground.
Mr Whittam said: "There is evidence of purchases he made by email being sent straight to Northern Ireland.
"Delivery of some of those chemicals and equipment, they went to that address of his late grandmother's.
"There is evidence he travelled to Northern Ireland by ferry.
"It looks as though some items must have been taken by him from England to Northern Ireland. For example, the bullets.
"There is concern he might have found it easier to travel between England and Northern Ireland because of the ID he would have had."
Mr Whittam said the serviceman, who is originally from Larne in Co Antrim, had apparently been motivated by "a connection with dissident Republicanism".
Maxwell faces years behind bars when he is sentenced after pleading guilty in February 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.
Maxwell appeared today via video link from Woodhill prison in Milton Keynes, where he sat at a desk with a laptop, making notes, wearing a white Nike t-shirt.
Mr Whittam said the serviceman had been attacked in 2002 and had a copy of a news report about the assault on his laptop.
He said: "This is an image recovered from a laptop at his home address.
"It's a report in the Republican News from July 11 2002.
"It's headed 'Sectarianism never sleeps in Larne'.
"This defendant, aged 16, being subject to a brutal attack with, as it's reported, iron bars and golf clubs and suffering a compound fracture of his skull.
"We know of nothing that traces this offending to that attack.
"But if it's urged in mitigation that any behaviour was as a result of this attack, my Lord would have to balance that to considering, if he was aggravated since 2002 did that influence his decision in joining (the Marines)?"