But as the Madrid bombings demonstrated, the potential for terrorism on the rails is growing.

In the aftermath of the Madrid bombings, fingers were pointing all around.

"We don't know how big a factor the Madrid bombing was in the outcome," one senior American official said.

He did not answer the question of whether the Madrid bombings had influenced the Spanish elections.

Several people believed responsible for the Madrid bombings were well known to security services elsewhere in Europe.

My usual, post-9/11 anxiety was heightened by the Madrid bombings of a few days before.

They, too, had fallen under surveillance by security services before the Madrid bombings, officials here said.

Investigators were still trying to determine whether the group was responsible for the Madrid bombings on Thursday.

European growth in 2004 was forecast to be the weakest among the world's regions even before the Madrid bombings.

He was also wanted in Spain over the Madrid bombings.