Hillary Clinton speaking about Northern Ireland ahead of her visit there
A deal on policing in Northern Ireland is "within reach", US Secretary of State Hillary Clinton has said.
Speaking at a meeting in Dublin with Irish Prime Minister Brian Cowen, she said the devolution of justice powers was an "essential milestone".
She had earlier met Gordon Brown at Chequers and has arrived in Belfast for more talks as part of a tour of Europe.
Her visit came as the Irish National Liberation Army (INLA), a republican paramilitary group, renounced violence.
The group, which was responsible for dozens of murders during Northern Ireland's Troubles, issued a statement saying its "armed struggle is over".
Mrs Clinton said: "The step of devolution for policing and justice is an absolutely essential milestone.
Mark Simpson, BBC News, Belfast
The visit to Stormont may turn out to be one of the easiest stages of the five-day European tour by US Secretary of State, Hillary Clinton.
The curse of foreign diplomacy is arriving in a country and constantly needing ministerial aides to whisper in your ear the names of leading politicians. Mrs Clinton will not have that problem in Northern Ireland.
She has been to Stormont so often - as First lady, Senator and now as Secretary of State - that she is on first name terms with most of the key players. Indeed, she probably knows their spouses' names too.
Resolving the differences between Sinn Fein and the Democratic Unionists may need more than some high-powered American charm and gentle words of persuasion.
Mind you, the indomitable Mrs Clinton will try her best.
"Clearly there are questions and some apprehensions, but I believe that due to the concerted effort of the British government, Irish government and support of friends like us in the US, that the parties understand this is a step they must take together.
"It will take the leaders of both communities working together to continue not only the devolution but then to make day-to-day governing a reality, and I'm confident that that is within reach."
BBC Ireland correspondent Mark Simpson said Mrs Clinton's visit had already had an influence in Belfast even before she arrived.
He said: "The political atmosphere has improved and up at Stormont the gap between the parties, which was very wide, has narrowed a little - there has been progress made in recent days.
"It's a little like if there's a family row going on and you know there's a very important group of visitors coming, you try to patch up your differences."
Sinn Fein and the DUP have been at loggerheads over when powers for policing in Northern Ireland should be devolved from London.
The former party says it should have already happened, while the latter has been more cautious, saying it will only assent to devolution with an adequate financial package in place and broad community confidence.
Speaking in London, where she met British Foreign Secretary David Miliband, Mrs Clinton said a rise in dissident republican activity in Northern Ireland was "out of step" with the peace process.
It was "imperative" the Good Friday Agreement was "seen all the way to conclusion", she added.
Those who would try to disrupt the peace of people going about their daily lives are out of step and out of time
At a meeting with Prime Minister Gordon Brown, Mrs Clinton restated her faith in the US-UK "special relationship".
The situation in Northern Ireland, the Afghan war, concerns over Iran's nuclear programme and climate change were said to be on the agenda at Chequers.
The two politicians also discussed the current situation in Pakistan and India.
During her visit to the UK, Mrs Clinton also spoke of her admiration for the "incredible courage and commitment" of British troops in Afghanistan.
Mr Miliband paid tribute to Mrs Clinton's "personal commitment" to the peace process in Northern Ireland for more than 15 years.
Mrs Clinton said: "Those who would try to disrupt the peace of people going about their daily lives are out of step and out of time."
Asked about the potential that financial support was being provided by US sympathisers, she added: "There is no support... the best we can tell is that those who try to inflict harm on others and cause damage are funding their evil enterprise from criminal gains and we hope to see an end to all of that."
Police have recently begun an operation aimed at disrupting what is seen as increased dissident republican activity this year.
Mr Brown recently held a series of meetings with Sinn Fein and the DUP on the timing of the transfer.
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