US Secretary of State Hillary Clinton on Monday asked Northern Ireland's leaders to finish the work of the Good Friday accord by agreeing on a timetable for transferring police and justice powers from Westminster.
Clinton's visit to Northern Ireland coincides with the announcement that a terrorist group is going out of business.
The Irish National Liberation Army, which murdered the MP Airey Neave in 1979, declared "the armed struggle is over" yesterday, in a statement delivered over the grave of its founder Seamus Costello.
After meeting with the Irish Prime Minister Brian Cowen in Dublin, Clinton said remaining differences can be overcome.
"Clearly there are questions and some apprehensions," she said.
"But I believe that due to the concerted effort of the British government, the Irish government, the support of friends like us in the United States, that the parties understand that this is a step they must take together."
Clinton stressed the need to fully implement the peace process started by the 1998 Good Friday Agreement, which ended three decades of violence in Northern Ireland which killed at least 3,500 people.
Earlier in London, Clinton hailed the historic special relationship between Britain and America as she flew into the capital on a whirlwind visit to consult on the crises in Afghanistan and Iran.