The dissident republican Real IRA, which claimed responsibility today for a car bomb attack on MI5's headquarters in Northern Ireland, will not derail the peace process, political leaders said.
One man was injured in the 12.24am attack at Palace Barracks in Holywood, Co Down, which was timed to coincide with the devolution of policing and justice powers from Westminster to the Stormont Assembly.
A taxi driver in north Belfast was held hostage for two hours before he was forced to drive the bomb to the base in his car.
Security personnel were evacuating the area when the device exploded and some of the 30 to 40 residents who were fleeing the scene at the time described diving for cover to avoid shrapnel from the blast.
As security sources confirmed they were investigating a claim of responsibility by the Real IRA, First Minister Peter Robinson condemned the attack, while Deputy First Minister Martin McGuinness insisted the peace process remained "rock solid".
Secretary of State Shaun Woodward said: "Today Northern Ireland will complete devolution with the transfer of policing and justice powers to Stormont.
"That democratic transition stands in stark contrast to the activity of a criminal few who will not accept the will of the majority of people of Northern Ireland.
"They have no support anywhere."
The Real IRA has been linked to a string of attacks against security forces and last year shot dead two soldiers at Massereene Army base in Co Antrim.
The latest attack came after law and order powers were transferred to Northern Ireland at one minute past midnight.
Later today, politicians at the Assembly are to select a Justice Minister to lead the new Department of Justice.
The devolution move was agreed in the Hillsborough Castle Agreement brokered in February between the Democratic Unionist Party (DUP) and Sinn Fein.
But while the development will bring a raft of new powers into the hands of Stormont politicians, responsibility for national security and related intelligence-gathering is not to be transferred.
The high-security MI5 facility is therefore the most potent symbol of the security service's continuing role in Northern Ireland.
The MI5 base was built in 2006 at a reputed cost of more than £20 million.
The four-storey building is said to house 400 staff and has been described as the organisation's largest base outside London.
The blast follows a series of attacks by dissidents in Northern Ireland.
In January, Police Service of Northern Ireland (PSNI) officer Peadar Heffron was seriously injured in an under-car bomb attack in Co Antrim.
This was followed by a car bomb which damaged a court building in Newry, Co Down, in February.
The latest attack also comes in the wake of the first anniversary of the deaths of two British soldiers - Mark Quinsey, 23, and Sapper Patrick Azimkar, 21 - who were gunned down by the Real IRA outside Massereene Army barracks in Antrim town in March last year.
Two days later, PSNI Constable Stephen Carroll was murdered by the Continuity IRA in Craigavon, Co Armagh.
But Sinn Fein's Mr McGuinness said his party's peace strategy remained strong and that the dissident groups had no support and would not derail the political process.
"The process is difficult and has raised many challenges for people as we move forward, but I think that people are also conscious of the fact that we are now part of power-sharing institutions on the basis of partnership and equality, that we are in ministerial positions in the north, which are linked to all-Ireland institutions," he said.
"I think there is no misunderstanding whatsoever of where republicans are coming from. The vast majority of republicans, the vast majority of the people of Ireland, support what we are doing."
He added: "There are challenges and we have to rise to those challenges, but where people are trying to destroy the peace process, as these people are, of course, in my view, there is not even the remotest prospect of them succeeding."
He added: "The peace process is rock solid."
Mr Robinson said the bombers would not disrupt the devolved government.
"We are not going back, we will continue to move forward," said the DUP leader.
Mr Robinson told the BBC the bomb was aimed at putting pressure on politicians.
He added: "It is an attempt to intimidate Assembly members as they meet today to move forward on policing and justice."
Alliance Party deputy leader Naomi Long said the attack appeared to be an attempt to "drag Northern Ireland back into the past".
She said: "I would utterly condemn any such attack and am sure that the vast majority of people from across our community are sickened by the actions of people who seem intent on dragging Northern Ireland back into the past.
"It is vital that all local politicians unite to condemn this attack and redouble our efforts to create stable political structures and a peaceful society.
"I would also appeal for anyone with information about this incident to contact the police so that those behind the attack can be apprehended."
Her party leader, David Ford, is expected to be elected into the Justice Minister's job at Stormont today.