The 1986 – 1989 period saw an increase in the terror activity of the ETA Basque separatist group . This reached its peak with the Hipercor bombing on 19 June 1987 , which — with 21 dead and 45 injured — would eventually become the deadliest attack in ETA 's history . Other deadly attacks included the Plaza República Dominicana bombing on 14 July 1986 , three weeks after the previous general election and one day before the newly elected Cortes re-assembled , which left 12 dead and 32 injured ; and the 1987 Zaragoza Barracks bombing , with 11 dead — including 5 children — and 88 injured . Concurrently , the PSOE government introduced a policy of dispersion of imprisoned terrorists throughout the entire Spanish territory in order to restrict contacts between them and prevent terrorist organizations from organizing themselves from prison . Political parties signed several anti-terrorist agreements , such as the Ajuria Enea Pact or the Madrid Agreement on Terrorism , aimed at increasing inter-party cooperation on the issue . In January 1989 , ETA declared a ceasefire in order to start negotiation talks in Algiers with the Socialist government , but no successful conclusion was reached and ETA resumed its violence campaign
Plaza República Dominicana bombing
Plaza República Dominicana bombing
1989 Spanish general election