President Clinton has just completed his third and final official trip to Northern Ireland. It was a well-deserved victory lap, despite an outcome still in doubt. It was a mission of large-scale hope, sandwiched between two small incidents that illustrate the resilience of despair.

No president has invested as much in Northern Ireland as has this one and, given the likelihood of failure, risked so much. After more than 300 years of strife between Protestants and Catholics and the last 30 years of bloody terrorism, Northern Ireland seemed a lost cause until American leaders – Mr. Clinton and Sen. George Mitchell, principally – became involved. The 1998 Good Friday Accord would not have been reached without them and because of that peace agreement Northern Ireland now has the chance to become a civil society.

This trip produced no major proposals. Mr. Clinton’s intent clearly was to remind Northern Ireland of the substantial political issues still to be resolved, such as reform of the predominantly Protestant police force, IRA disarmament, international coordination of anti-terrorism efforts and, perhaps most troubling, the tendency of leaders on both sides to threaten to scrap the accord as a bargaining tactic. Overall, however, the significant decline in sectarian violence is a visible sign of progress.

But the two small incidents show how fragile this progress is. In the first, just a few days before Mr. Clinton arrived, a Protestant taxi driver was killed in a terrorist attack – by Protestant terrorists. A call to lure a random victim was made to a Catholic-owned cab company, all of their cabs were busy, so, in the new spirit of cooperation, it was transferred to the Protestant company. After killing the wrong man, the terrorists went out and murdered a Catholic to even the score. These senseless acts resulted in two funerals, two grieving families and the prospect of retaliation.

The second was not violent, but demonstrated the intractability that leads to violence. Mr. Clinton’s major speech of the visit was before 8,000 at a Belfast arena. Protestants and Catholics sat side by side, cheering the American who had helped make that seating arrangement possible. One lone heckler shouted the president down; the president’s polite offer to engage the young man in conversation rather than conflict was met with insult. One angry voice can, if allowed, drown out the cheers of thousands.

It is unlikely that the next president will devote so much attention to Northern Ireland. President-elect Bush already has signaled a lessening of American involvement in the internal affairs of other nations, he calls it a more “humble” foreign policy. This may, in the case of Northern Ireland, be good, even necessary.

The British and Irish governments have shown of late an increasing dependence upon the United States as a mediating force and as a solution to the problems they must solve for themselves. The fate of Northern Ireland does not, for example, depend upon the U.S. State Department designating the Real IRA as a terrorist organization, as several of Mr. Clinton’s hosts suggested. Renegade terrorist groups are but one problem facing Northern Ireland. It is but one of many problems that Northern Ireland ultimately must solve on its own.