Hillary Clinton's visit to Northern Ireland was partly designed as a lap of honour. The Clintons did play important parts in the peace process and are indeed to be ranked among the architects of the newly agreed institutions. But although Northern Ireland is held up as a model for conflict resolution, the process has not been an unalloyed success. The ugly scenes that preceded the Secretary of State's visit meant she was obliged yesterday to condemn the negatives as well as commending the positives.

Those positives include a transformed city, a distinctive new spirit and much-improved political relations in an evidently stable settlement. Unionist Peter Robinson and republican Martin McGuinness both paid warm tribute to Hillary Clinton yesterday. Their cordial relationship is a strong sign that politics is working surprisingly well at the top, while the value of the process is indicated in the steep decline of violence since the worst days of the Troubles. But the violence has not disappeared, with a rump of republican dissidents continuing their futile, but occasionally lethal, mini-campaign against the security forces.

The major extreme Protestant groups, though still armed and dangerous, do not pose the same threat. But they, and young thugs from the loyalist ghettos, showed this week that they can cause much disruption. Neither the paramilitaries nor the youthful tearaways care what damage they inflict on Northern Ireland's image or economy. The recession has closed many shops, leaving businesses hoping that takings would be high today, traditionally one of the busiest days of the year. Instead, many Christmas shoppers will avoid Belfast city centre because a protest rally is to be held there.

One of the achievements of the peace process has been the gradual dismantling of ancient patterns in which Protestants dominated Catholics. As a result, a much fairer society is being constructed. But the problem, in the heads of many indignant Protestant ghetto-dwellers, is that steps towards equality are seen as yet more gains for Catholics at the expense of Protestants. They don't have much of a case, but they should of course be making their arguments by organising politically. Quite a few of them have come to realise this. But a small minority continues to resort to the nihilism of ugly rage. When the Clintons first visited Belfast less than two decades ago, people were still dying at the rate of dozens every year. Full-scale terrorism may have been vanquished, but the blight of ugly sectarian thuggery remains.