A truck full of bomb materials - more than twice the size of the Omagh bomb - was found in Northern Ireland on New Year's Eve.
The Police Service of Northern Ireland say they foiled a dissident attack after they found an articulated truck packed with 1000lb of explosives under a flyover bridge on the A1 road near Newry. The newly refurbished A1 is a roadway linking the North and South.
Police say the materials found in the truck could have fueled a powerful explosive device or a number of smaller devices.
It is believed the lorry had been driven from the Republic.
Security experts in the North say that the threat of a serious attack has never been higher. They say there had been concerns that dissidents would attack over Christmas or the New Year.
Shoppers and businesses were urged to watch out for suspicious activities, particularly when shops are very busy.
Security officials on both sides of the border estimate that there are now more than 200 active dissident republicans.
The Real IRA and Continuity IRA are mainly responsible for all dissident activity. Both terrorist organizations mount operations and collaborate with each other.
The Minister for Justice Dermot Ahern has said that dissidents are intent on remilitarising the border between both states. Minister Ahern said that the dissidents had been able to recruit new members in the North but activity was confined to the "usual suspects" in the South. Minister Ahern also said that the police in the south had carried out successful raids against dissidents this year.
The Independent Monitoring Commission has confirmed that some former members of the Provisional IRA have been in subversive activity with dissident republicans. The MI5 is Britain's intelligence service and placed its threat level at severe.