Police in the North are conducting fresh searches as part of a terrorism investigation which prompted the arrest of a British Royal Marine.
Ciaran Maxwell, 30, from Larne, Co Antrim, was detained by Metropolitan Police officers in southern England during a pre-planned swoop last week. He is still being questioned.
It is understood the operation is linked to the discovery of two dissident arsenals in woodland in Northern Ireland earlier this year and today's renewed activity by officers is being carried out nearby.
A PSNI statement said: "Police are conducting a search in the Inver Road area of Larne linked to the ongoing investigation into Northern Ireland-related terrorism which has resulted in the arrest of a 30-year-old member of the armed forces in Somerset last week."
Last Wednesday's arrest operation involved searches at a house and wooded area in south Devon, England.
Searches at the property in Exminster and nearby Powderham New Plantation woods continued the following day.
In Northern Ireland, officers searched a number of properties in Larne last Wednesday - near the two forest parks where the weapons dumps were unearthed earlier this year.
Maxwell is being detained on suspicion of preparation for acts of terrorism.
While the threat posed by violent dissident republicans in Northern Ireland has been classified as severe for a number of years, in May the UK intelligence services raised the threat level in Great Britain from moderate to substantial.
Two separate hauls of weapons were discovered in Carnfunnock and Capanagh parks within three months of each other.
An armour-piercing improvised rocket and two anti-personnel mines were among the cache recovered at Capanagh in May.
Several pipe bombs, magazines and ammunition for an assault rifle as well as bomb component parts and command wires were also concealed in barrels in purpose-built holes in woodland.
In March, bomb-making items were found at nearby Carnfunnock Country Park.
Police said four barrels were unearthed at Carnfunnock - two barrels were empty but two contained a variety of bomb-making components, including wiring, toggle switches, circuit boards, partially constructed timer power units, ball bearings and a small quantity of explosives.
Larne is predominantly unionist/loyalist in community make-up, so the discovery of the finds led to some initial speculation that they could be linked to loyalist paramilitaries.
However, after assessing the nature of the weaponry, police concluded they most likely belonged to dissident republicans.
Since 2009, dissidents have murdered two soldiers, two policemen and two prison officers in the North.