Hillary Clinton said the US would not meddle in the transfer of policing and justice powers
US Secretary of State Hillary Clinton has said the devolution of policing and justice powers is an issue for the Northern Ireland Assembly alone.
"The Obama administration and the United States is committed to helping you on your journey," she said.
"But when it comes to the important issue of the devolution of policing and justice, that is a decision for this assembly to take."
Mrs Clinton was addressing MLAs at Parliament buildings on Monday.
"As a true friend, my hope is that you will achieve what you set out to do... to complete the process of devolution," she told assembly members.
She was speaking as talks to transfer policing and justice powers continue.
The financing of the deal on those powers has been a major sticking point in recent weeks, with a series of intensive talks held between Gordon Brown and NI's leaders.
A letter detailing Mr Brown's financial offer to pay for the devolution move was delivered to NI's first and deputy first ministers on Monday.
Mrs Clinton's address followed talks with the the ministers at Stormont Castle.
Gareth Gordon, BBC News, Belfast
Hillary Clinton delivered a carefully worded speech praising the progress that has been made.
But she warned that peace and economic progress go hand in hand and that the global economic downturn threatened some of the gains made in the past decade.
It was not the US's intention, she said, to meddle in the devolution of policing and justice but she made clear what she wanted to happen.
At the end, she was given a standing ovation although two DUP MPs did not take part.
William McCrea and Gregory Campbell left while the rest of the chamber was on its feet applauding.
DUP First Minister Peter Robinson welcomed the US Secretary of State saying that Northern Ireland had "come a long way".
"Of course there are difficulties, but we are committed to making it work," he said.
The Deputy First Minister, Sinn Fein's Martin McGuinness, said Hillary Clinton had been "a true friend" to Northern Ireland, offering strong intellectual, emotional and political support.
After discussions on policing and justice at Downing Street on Thursday, Mr McGuinness had said all sides were "on the cusp of agreement" on policing.
Mr Robinson said the recent negotiations with the prime minister had won "millions of pounds" more for the policing and justice budget.
However, Mr Robinson has made clear that finance is not the only issue.
He said there also needs to be confidence among the unionist community that the time is right to devolve the powers.
Whilst the DUP have welcomed Mrs Clinton's visit, they have made it clear that her presence will not pressure them into reaching a deal.
After her speech at Stormont Mrs Clinton attended an engagement with business leaders at Queen's University before moving onto a civic reception at Belfast City Hall.
Coinciding with her visit, US software company NaviNet announced its new £4.4m research centre in Belfast would create 60 jobs over three years.
BBC Northern Ireland political editor Mark Devenport said Mrs Clinton seemed to be linking the prospect of further US investment with achieving the devolution of policing and justice.
"When the Northern Ireland Secretary Shaun Woodward tried something similar he was met with a fairly scornful response from the DUP," our correspondent added.
"The Americans are still pushing that message, maybe in a slightly more nuanced way than Shaun Woodward."