Security services on high alert over Easter Rising centenary threat
Security services on both sides of the border have been on high alert over a threatened hijacking of Ireland's centenary commemorations by dissident republicans.
In the last two months the danger has been warned of at least twice by experienced officers.
The big concern is that terrorist splinter groups will attempt a spectacular as the Republic honours those who fought and died in the 1916 Easter Rising - a bloody rebellion against Britain which the dissidents claim to keep alive.
Among these small but lethal renegade groups are the Continuity IRA, the Real IRA, "new" IRA and Oglaigh na hEireann (ONH).
While an attack on the Republic's soil is virtually unheard of, any one of these closely monitored hardcore factions would look upon preparations to mark the Rising on Sunday March 27 as fertile ground to justify murder.
It would also garner huge publicity with an estimated 250,000 people lining the streets of Dublin and an international audience for the biggest commemoration the Irish state has ever seen.
President Michael D Higgins will lead a series of events over several hours from honouring the executed rebel leaders such as Patrick Pearse and James Connolly in Kilmainham Gaol to the raising of the Tricolour and reading the Proclamation at the GPO on O'Connell Street.
Dissident terrorist numbers are small but in the ceasefire era they have routinely attracted disaffected youth in disadvantaged estates in Northern Ireland.
One of the Republic's most senior police officers, Assistant Garda Commissioner John O'Mahoney, warned in January that the threat of an attack around the period of commemorations was "very much in mind".
A similar assessment was made by PSNI Assistant Chief Constable Will Kerr a year earlier and only weeks ago the Police Federation for Northern Ireland expressed the same fears after shots were fired at officers in Lurgan, Co Armagh.
There has also been repeated disruption to the Dublin-Belfast rail line in recent months.
It would not be the first time that dissidents tried to use historically significant events to launch a spectacular.
During the Queen's visit to Ireland in 2011, what the Real IRA called the "final insult", a number of suspects were arrested and a pipe bomb was found on a bus bound for Dublin on the first day of the trip.
A number of people are awaiting trial in the Special Criminal Court in Dublin in relation to incidents.