Leading article: The Clinton approach to Ireland has been vindicated

Clear signs of progress will greet the US Secretary of State this week

When Hillary Clinton first became involved with Northern Ireland, as she did along with her husband Bill, many thought the Irish question was simply insoluble. As prime minister, John Major was so appalled when Mr Clinton allowed Gerry Adams into the US, after years when the Sinn Fein leader had been banned, that for some time he refused to take calls from the president.

But the American initiative worked, if at some temporary cost to the state of the London-Washington relationship. In advance of that last Conservative government, the Clintons concluded that Mr Adams and Martin McGuinness were on a journey away from terrorism and into politics. Permitting Mr Adams to enter the US was hugely daring. Yet its correctness will be amply demonstrated today when Hillary Clinton, as US Secretary of State, addresses the Northern Ireland Assembly in Belfast.

That Assembly is slow-moving, expensive to run and not particularly efficient. In the past few years it has seen wrangles and periods of near-deadlock. Responsibility for many areas of life has been devolved to it, including agriculture, education and transport. But its government, which includes both loyalists and republicans, has barely begun the task of working out how to improve relations in a deeply divided community.

First Minister Peter Robinson, leader of the Democratic Unionist Party and the Deputy First Minister, Martin McGuinness, lead the Assembly. They have for months failed to reach accord on the last piece of the devolution jigsaw, the transfer of power over policing and justice matters. Over the weekend it began to look as though they and Gordon Brown had finally reached an agreement, although fingers remain crossed in London and Belfast. Even if it does work, more turbulence lies ahead, for example when the Westminster election campaign begins to generate heightened rhetoric.

So it is that while members of the Assembly will applaud Hillary's remarks today they are unlikely to link arms in a show of fellow-feeling. At the same time, for all its shortcomings, the Assembly and indeed the peace process in general stand as a monument to the triumph of politics.

Some of the more extreme shores of both republicanism and loyalism have taken a long time to absorb the lesson that power does not necessarily come from the barrel of a gun and that politics, if given a chance, can deliver. The latest organisation to grasp this crucial message is the Irish National Liberation Army (INLA), a small but well-armed and sometimes lethal republican grouping. Yesterday it declared that its "armed struggle" was over and that it would now pursue its objectives "by exclusively peaceful political struggle".

The most important loyalist paramilitary groups have recently sent out a similarly heartening message. Some dissident republican groups, such as the Real IRA, however, are proving exceptionally slow learners and remain committed to bombs and bullets. Nevertheless, Belfast's political landscape has changed dramatically since Bill and Hillary Clinton were first persuaded that a new era might lie ahead. Back in those days a republican such as Martin McGuinness was persona non grata. Today, he and Peter Robinson, both of them one-time symbols of militancy and obduracy, will jointly welcome Hillary Clinton. Her message will be to keep going.