"ALL Americans join Hillary and me in our outrage at the bomb explosion today in London," President Clinton said in a statement.
"I condemn in the strongest possible terms this cowardly action and hope those responsible are brought swiftly to justice. Our hearts and prayers go out to those injured in this terrible blast and to their families.
"I am deeply concerned by reports that the Irish Republican Army has announced an end to the ceasefire. For a year and a half, the people of the United Kingdom and Ireland have enjoyed living in pence, free to go about their daily lives without the threat of the bomb and the bullet.
"As was clear during my visit to Northern Ireland last year, people want pence. No one and no organisation has the right to deny them that wish.
"The terrorists who perpetrated today's attack cannot be allowed to derail the effort to bring peace to the people of Northern Ireland - a peace they overwhelmingly support.
"The United States stands ready to assist the two governments in continuing their search for negotiations and peace. Today's action underscores the urgent need for all sides to join in the fight against terrorism and to press forward in that search.
Senator Edward Kennedy condemned the bombing. It was "obviously an extremely ominous development", he said in a statement "but it's premature to speculate what it means for the pence process".
The co chairman of the Ad Hoc Congressional Committee on Northern Ireland, Mr Peter King, said, "I am distressed by the resumption of military activity and the breaking of the ceasefire."
Recognising the potential of the current situation and in order to enhance the democratic peace process and underline our definitive commitment to its success, the leadership of Oglaigh na hEireann have decided that as of midnight, Wednesday, 31 August, there will be a complete cessation of military operations. All our units have been instructed accordingly.
At this historic crossroads the leadership of Oglaigh na hEireann salutes and commends our volunteers, other activists, our supporters and the political prisoners who sustained this struggle against all odds for the past 25 years.
Your courage, determination and sacrifices have demonstrated that the spirit of freedom and the desire for peace based on a just and lasting settlement cannot be crushed. We remember all those who have died for Irish freedom and we reiterate our commitment to our republican objectives.
Our struggle has seen many gains and advances made by nationalists and for the democratic position. We believe that an opportunity to create a just and lasting settlement has been created.
We are therefore entering into a new situation in a spirit of determination and confidence, determined that the injustices which created this conflict will be removed and confident in the strength and justice of our struggle to achieve this.
We note that the Downing Street declaration is not a solution, nor was it presented as such by its authors. A solution will only be found as a result of inclusive negotiations. Others, not least the British Government, have a duty to face up to their responsibilities.
It is our desire to significantly contribute to the creation of a climate which will encourage this. We urge everyone to approach this new situation with energy, determination and patience.