In early June British officials held two meetings with Sinn Fein, and a third was scheduled for last week. The sessions’ goal was to restore the ceasefire and engage Sinn Fein in the talks, which are aimed at achieving a settlement that would command the support of both communities. Progress seemed possible.

Then, last week, with shocking brutality, two police officers in Northern Ireland were murdered, each shot several times in the back of the head at close range. The IRA quickly claimed responsibility, and the British government called off all further contact with Sinn Fein. Progress toward peace again seemed a distant dream.

Is it? I may be an incurable optimist, but I believe a historic opportunity to end centuries of conflict in Northern Ireland still exists. If it’s not seized now, though, it may be years before we have another chance, and the failure could cost many lives on both sides.

It’s worth pursuing a political settlement for one overriding reason: the overwhelming majority of people in Northern Ireland want political stability and reconciliation. To give up now, to succumb to despair and sectarian war, would be to declare that a handful of men of violence are winners and the rest of the people are losers. That’s a result I’m not prepared to accept.

The next few months are critical. First, the marching season must pass without violent incident. That’s when each side celebrates its history with an estimated 3,000 summer marches, most of them by Protestant organizations. There was widespread rioting during last year’s season. A repeat this year could doom the talks, discourage economic investment and devastate Northern Ireland tourism. Today, urged on by business and church leaders, local newspapers and Secretary of State Mowlam, people in both communities are working feverishly to avoid that result.

Second, the IRA must immediately restore its ceasefire. At the G-7 meeting in Denver last weekend, Blair said he would give Sinn Fein one last chance to enter the talks. The police officers’ murder by the IRA was reprehensible and should be unequivocally condemned; it should be the last such atrocity in Northern Ireland’s troubled history. And both sides must find a way to make progress in the talks on substantive issues. I know they can do it. For more than a year I’ve met with each side’s political leaders, listened to them, worried with them. For the most part they’re men and women of intelligence, experience and determination. But, like all of us, they and their communities are products of their history - and their history is one of centuries of conflict. It isn’t easy to go against community attitudes; it’s harder still to change them. But I know these men and women well enough to know that they can successfully turn the tide.

Third, the twin demons of Northern Ireland - violence and intransigence - must be overcome. They feed off each other in a deadly ritual in which most of the victims are innocent. During the past two years I’ve come to know and admire the people of Northern Ireland. They’re energetic and productive. They deserve a better life than they’ve had. Of course, there are those who don’t want anything to change, ever. They want to re-create a past that is gone forever. But their way will only guarantee never-ending conflict. It will ensure that the next half century is as full of death and fear as was the past half century. If, on the other hand, we can end the violence and people can live free of fear, then gradually the walls of division will finally come down.

I’m constantly asked by Americans concerned about Northern Ireland, ““What can I do?’’ Here’s my answer: The American people, and especially the leaders of the Irish-American community, must say clearly and repeatedly that they condemn violence, that they demand its end, that they will not support those who engage in or condone violence. They must say it publicly, loudly and forcefully. Political violence, from whatever source, is morally wrong. It’s counterproductive. It deepens divisions. It increases hatred. It hurts innocent people. It makes peace and reconciliation more difficult to attain. It must end.

After his election, to emphasize its importance, Prime Minister Blair chose Northern Ireland for his first trip outside London. In a speech there he said: ““I am ready to make one further effort to proceed with this inclusive talks process. My message to Sinn Fein is clear. The settlement train is leaving. I want you on that train. But it is leaving anyway, and I will not allow it to wait for you. You cannot hold the process to ransom any longer. So end the violence. Now.''

So the process must and will move on. Only the outcome is in doubt. Some have said that the political talks are all that’s preventing widespread war. But as the participants in those talks know better than anyone, they cannot go on indefinitely. They must either move forward or end in failure. For the people of Northern Ireland, the time for decision is now.