After Basque separatist group ETA announced Tuesday the end of its ceasefire, The Spanish Prime Minister vows to fight back with the “same firmness and determination” with which he pursued peace talks with the group.

ETA ended its 15-month ceasefire Tuesday, accusing the government of hindering the ongoing peace process. An incident in December 2006, when two persons were killed in a bomb attack, determined the Spanish government to forego peace talks with the group.

ETA had not had such attacks since it first announced the ceasefire in March 2006. In December, the organization claimed it had not meant to kill anyone and that the ceasefire continued.

The declaration that the ceasefire would end was made via the Basque newspapers Berria and Gara, warning ETA would “be active on all fronts to defend the Basque Country.”

Spanish Prime Minister Jose Luis Rodriguez Zapatero has reacted to the news by saying Wednesday that he vows to ETA separatists with the “same firmness and determination” which he showed while trying to reach peace the group.

Zapatero called for unity among political parties.