Global Networking: Trading in Terror?

For years, the Irish Republican Army has been courting terrorist groups across Europe and the Middle East — training its men in Palestinian camps in the '70s and '80s, acquiring arms from Libya in those same decades, and building close ties with ETA, the Basque separatist group. So when three suspected high-level I.R.A. members were arrested three weeks ago in Colombia after visiting the jungle stronghold of a cocaine-funded rebel army, the conclusion was that the I.R.A. had added yet another link to its global network of friends.

The I.R.A. is not alone in its Latin outreach campaign. Even...