The recent announcement by the Basque separatist group Euskadi Ta Askatasuna (ETA) that it is ending terrorist operations altogether is more significant than anyone not closely following Basque nationalism might suspect. ETA has killed more than 800 people in a terrorist campaign that dates back to Francisco Franco's time. The group did not say it would disarm, and it did not express regret for past activity. But it did really say it was quitting terrorism; it was not merely announcing another of the many cease-fires that it has declared and then abandoned. Perhaps the closest equivalent to its declaration was a statement in the 1990s by the leading German leftist terrorist group, the Red Army Faction, that it had found terrorism to be a dead end and was going out of business.

ETA isn't exactly going out of business, and the issue of Basque separatism, or at least demands for greater autonomy, will persist. The Spanish government will have a hard time defusing the issue, partly because it would be hard to expect it to grant even more autonomy than the Basque region already enjoys. But what it should not do is follow the example of the government of Sri Lanka, which, since its military victory over the Tamil Tigers, has shown insensitivity toward the needs and sentiments of the Tamil population.

ETA's step has some lessons for the handling of other violent groups, even ones with goals and circumstances much different from ETA's. One is that cracking down physically on a group is not necessarily incompatible with influencing its decisions in a direction that moves it away from violence. The weakening of ETA through the operations of Spanish and French security forces was probably a major factor behind its announcement. The Pakistani government ought to take notice instead of complaining that U.S. policy toward the Haqqani group, and the demands it makes on Pakistan regarding the group, appear to vacillate between cracking down and negotiating.

Another lesson is that even seemingly incorrigible terrorist groups are capable of learning from others and changing their ways. ETA's announcement followed an appeal by an informal, unofficial group of negotiators who included Sinn Fein Leader Gerry Adams. One can hope that ETA will follow the example of the Sinn Fein's longtime terrorist wing, the Provisional Irish Republican Army, in eventually giving up arms and violence completely.

A final lesson is that most victories in counterterrorism, even when coming in a distinctive or unusual form such as ETA's announcement, will be incremental and unclear. That is not a reason to dismiss them. It is a reason to attempt to build on them.