Clifford D. May is president of the Foundation for Defense of Democracies, a policy institute focusing on national security.

...George Will, the venerable columnist, once cited Northern Ireland as one of the world’s two “intractable” conflicts. The other was what was then known as the Arab–Israeli conflict, today more usually called the Palestinian–Israeli conflict, though in reality it is now Islamist regimes and movements that are most seriously waging what they call a jihad against Israel....

On a brief return to Northern Ireland this week, it was apparent that there are still tensions, still segregated neighborhoods, still pubs where Protestants and Catholics do not mix. But the Troubles ended when most people on both sides accepted the idea of an imperfect peace, when they came to see compromise as preferable to more killing and dying, and when they tired of the poverty and degradation that chronic carnage brings in its wake....

Should that give us hope that peace in the Middle East also is possible and perhaps even imminent? Absolutely not.

At its worst, the IRA never sought the destruction of Britain and never vowed to wipe Protestants off the Irish map. The most extreme Protestant paramilitaries did not argue that southern Catholics had no right to self-determination....