In a letter published Thursday by the Basque newspaper Gara, Arnaldo Otegi said Spain’s reaction to ETA’s announcement that it is ending its violent campaign for Basque independence simply reflects the country’s insecurity.

He said Spain could no longer use ETA as an excuse for not dealing with the conflict.

Otegi was convicted of terrorism last month and sentenced to 10 years for trying to reform ETA’s banned political wing, Batasuna.

He is seen as a key figure in getting ETA to cease its 43-year-long bombing and shooting campaign that killed 829 people. ETA is considered a terrorist organization by Spain, the European Union and the United States.