They said the rockets pose a new threat by the terrorists, as do their use of mobile phones to remotely detonate explosives. Security chiefs also fear dissidents will use the 1916 centenary to launch attacks.
Gardaí yesterday warned that not only were dissidents becoming more sophisticated in their capabilities, but were recruiting young people, some of whom were displaying engineering skills.
Assistant Commissioner John O’Mahony, Garda Crime and Security Branch, said there was a “very real threat” from the dissidents, particulary in the North.
It follows comments from PSNI assistant chief constable Will Kerr last October, who warned that a dissident terror attack there was “highly likely”. He also said dissidents would aim to ramp up their violence in the run-up to the 1916 centenary.
Mr O’Mahony said dissident groups were displaying growing technical knowledge and skills.
“There is a steady and growing rise in dissident republicans becoming more sophisticated. From some of these devices, and the way they are operated, there are increasing signs of sophistication in relation to engineering,” he said.
Detectives from the Garda national security units seized four rockets last year, including two large ones, modelled on the Kassam rockets used by Hamas in attacks on Israel — the first seizures of their kind here.
They were put on display at Garda headquarters yesterday, along with Semtex, explosive components, mortars, rifles, machine guns, and ammunition seized from dissidents in the last two years.
Gardaí said the large rockets were “prototypes” and that dissidents were developing them to use on major targets, such as PSNI and British army stations.
Experts said the rockets have a maximum range of 6km and could store a couple of kilograms of Semtex, enough to create a “50ft blast zone” on impact.
The weapons are crude and can only be directed by changing the degree of their trajectory. Gardaí believe dissidents are working on designing guidance systems and are conducting tests in remote locations.
Mr O’Mahony said he believed “without hesitation” gardaí foiled planned attacks by dissidents on Queen Elizabeth and Prince Charles in their respective visits here in 2011 and 2015.
Sinn Féin president Gerry Adams said he “accepts entirely” that dissidents were active and posed a real threat: “In the centenary year of 1916, I would love those groups to seize this year to get off the scene.”