President Clinton has said he holds "no illusion" that his visit to Northern Ireland "is going to solve all the problems".
Speaking by satellite to a student audience in Boston, he said finding solutions to Northern Ireland's problems "is something the parties and the governments have to do". He warned that failure to work on the issues could "lead to a cycle of recrimination and potentially even to a return of violence and the Troubles".
He hoped his visit would "encourage the political leaders and the people of Northern Ireland to continue working to overcome their differences and keep moving forward on the Good Friday accord."
Much had already been accomplished. "A local government is in place that represents all the people; ceasefires are holding; progress is made in putting paramilitary arms beyond use; significant work is being done in the vital areas of human rights, police and judicial reform. We are seeing a lot more investment from America and other countries in helping to create good new jobs."
But the President warned that if the momentum was not maintained, "then the gains would be put at risk".
He said: "It's easy to just focus on one part of this process, or one issue, and to complain. The difficult but far more important task is for everyone to keep his or her eyes on the big picture and to work through the issues."
Meanwhile, PA reported that the First Minister, Mr David Trimble, had written to President Clinton. Sources close to Mr Trimble said the letter "sets out the political context of the Clinton visit as David Trimble sees it, explaining why the institutions were suspended in February, how they were restored and the difficulties since then."
"It reminds President Clinton of his influence over republicans, and that his personal authority in the process could hold the key to resolving this issue once and for all," the sources told PA.